The Cycle (1978)

The film's plot centered on "the illegal trade in blood donations against the backdrop poverty and life in shanty-towns". A young man, Ali (Saeed Kangarani), takes his sick father (Esmail Mohammadi) to a hospital in Tehran. When his father is unable to be admitted, they wait outside the hospital and meet Sameri (Ezzatollah Entezami). Dr. Sameri offers them enough money for Ali's father's treatment if they assist him with some work. They meet him the next morning at a crossroads and get in a truck with some other people, unaware of what they will be doing or where they will be going. They arrive at a laboratory, where Ali's father is asked to give blood. He refuses, but Ali agrees to have his blood taken, and for that he is given 20 tomans. Sameri deals in blood - He buys the blood cheaply off of the poor and addicted, and sells it on to the hospital.
During Ali's dealings with the hospital, he meets Esmail (Ali Nassirian) and a young nurse, Zahra (Fourouzan). Ali begins working under Sameri, collecting donors for blood. Ali's father's health gradually worsens, until one day he dies. Ali dives deeper and deeper into blood dealing, and his new life begins.