Receptive females attract males with conspicuous postures and facial expressions. The gestation period of the female patas monkey has been estimated at 170 days. However, it is difficult to know the exact gestation period because the females show no external signs of estrus. Also, females in captivity can go through postconception estrus. Therefore, it is difficult to reliably estimate wild patas monkeys gestation periods based on captive specimans.
Females give birth to a single young.
Males transfer between groups when sexual maturity is attained. They wait for females to approach them. Males may have offspring with more than one female. However, it has been observed that extragroup males may join a group temporarily during a breeding season. Evidence for polygyny has been the fact that most groups contain only one adult male, and most males attempt to chase and threaten foreign males.