Dosti is the story of Ramnath or Ramu (Sushil Kumar) and Mohan (Sudhir Kumar). Ramu’s father Mr. Gupta, a factory worker dies in an accident. When the factory refuses to pay compensation, his mother passes out in shock by falling from the stairs. Ramu is injured in an accident and he becomes crippled. Thrown out of his home, crippled and penniless, he roams around the streets of Mumbai. Here he comes across Mohan, a boy who is blind and has a similar tale of woe. Mohan comes from a village. His sister, Meena had migrated from the village to Mumbai to find work as a nurse so that she could pay for her brother’s treatment. Mohan left the village after his caretaker died.

Ramu is good at playing the harmonica, while Mohan is a good singer. They team up and sing songs on the roadside and start earning money from passers-by. Ramu wants to finish his studies, and both of them befriend a small girl, Manjula (Baby Farida), who is the sister of a rich man, Ashok (Sanjay Khan). Manjula suffers from Rheumatoid Heart Disease and both the boys hope she would help them out.

Ramu and Mohan visit Manjula and ask for a loan of sixty rupees which is the amount required for Ramu's admission in school. But Manjula's brother rebuffs them and gives only five rupees. Feeling insulted, Mohan decides that he will raise the money by singing, which he successfully does. Ramu is admitted in the school after performing brilliantly in entrance test (he scores 294 out of 300). They move to a new house in a slum after someone tries to steal their hard earned money while they were sleeping on the footpath. Their new neighbor is Mausi, who lives with her teenage daughter and school going son, Nandu. Mausi treats them as her own sons.

In school, Ramu excels in studies despite being a regular target of ridicule of richer students who do not consider him their equal and often degrade him for being a "street beggar". The headmaster and teacher Sharma ji takes Ramu under their wings. Sharma ji also declared himself the guardian of Ramu. During a visit to Ramu's house, Sharmaji notices that the neighborhood is not fit for study and suggests that Ramu move in with him but Ramu does not leave Mohan. Meanwhile, one day while singing, Mohan hears someone (Ashok) calling out to Meena and rushes to embrace his long lost sister. But Meena is ashamed that Mohan has become a beggar and refuses to recognize him. Meena is looking after Manjula and there is a budding romance between her and Ashok. However, soon Meena confesses to Ashok. Ashok is sorry for her and consoles her that soon she will be together with her brother.

Mohan senses Manjula while sleeping and tells Ramu about it. Both decide to go and meet her, but she died. Ashok brings Mohan home one day and gives him Manjula's chime as her remembrance. When he tries to tell Mohan about Meena, Mohan lashes out in rage and says that he considers himself alone in this world, save for his friend Ramu.

Soon after, Ramu gets in trouble with some ruffians and as a result is mistakenly arrested by police during a burglary. Sharma ji goes to police station and bails out Ramu on the condition that he will live with Sharma ji and keep no contact with Mohan. Mohan is heartbroken and decides to visit him. But Sharma ji didn't allow him to talk to Mohan. Sad, Mohan roams the streets singing sad songs.

Sharmaji suddenly dies, leaving Ramu shattered. Ramu decides not to appear for the final exam as he cannot pay the fees. Hearing this, Mohan decides to raise the money once again by singing in streets in spite of his ill health. He successfully earns the money and pays the fees without Ramu knowing, but himself falls prey to illness and is admitted in hospital. In hospital, without telling him, Meena cares for Mohan as he recuperates.

Ramu comes first in the exams and comes to know of Mohan's sacrifice. He rushes to Mohan in hospital to ask for forgiveness where Mohan says that he was never angry with him. The doctor tells Mohan about Meena and he forgives her. The movie ends with all of them in a loving embrace.

• Sushil Kumar (real name Sushil Belani) as Ramnath 'Ramu' Gupta
• Sudhir Kumar (real name Sudhir Sawant) as Mohan
• Baby Farida as Manjula 'Manju'
• Sanjay Khan as Ashok
• Leela Mishra as Mausi
• Leela Chitnis as Ramu's mother, Mrs. Gupta
• Abhi Bhattacharya as Headmaster
• Uma Rajoo as Nurse Meena (Mohan's sister)
• Aziz
• Nana Palsikar as School Teacher Sharma ji
• Moolchand as Ashok's employee

The lyrics of the film are written by Majrooh Sultanpuri on music composed by Laxmikant Pyarelal. Dosti stands as a landmark in the career history of the musical duo as this won them their first Filmfare Award and made them popular in the film industry.^[3] Mohammad Rafi is the main vocalist for the songs.

Dosti collected Rs. 2 crore in the Indian box office and stood as third highest grosser of 1964. The first and second weekend collection was excellent.

The film stood out at the 12th Filmfare Awards in 1965 by winning six awards from seven nominations that it received. Dosti won maximum awards at the ceremony.

Won

• Best Film - Tarachand Barjatya
• Best Music Director - Laxmikant Pyarelal
• Best Story - Ban Bhatt
• Best Dialogue - Govind Moonis
• Best Playback Singer - Mohammad Rafi for the song "Chahoonga Main Tujhe Saanj Savere"
• Best Lyricist - Majrooh Sultanpuri for the song "Chahoonga Main Tujhe Saanj Savere"

Nominated

• Best Director - Satyen Bose