The young men, who were identified as Nasser Ch., Aref S. and Ali S., were accused of abducting and murdering a six-year-old boy in February 2002.
A week earlier five men were hanged in the Iranian capital and in the city of Ahwaz, also in Khuzestan.
Reza H. was hanged in public in Ahwaz in the early hours of the day. The four other men identified as Hatam Gorgi, Ali-Reza Hojabri, Mohammad Faranaki, and Ali-Reza Akbarian were all executed in Tehrans notorious Evin Prison.
Iran has the highest annual rate of executions in proportion to its population.