Reproductive patterns are highly variable among Neotropical colubrids. Snakes of the Tribe Xenodontini are widely distributed in South America and show continuous reproductive cycles in many areas. We report interspecific and intraspecific variation in reproductive traits among these snakes and also show that seasonal cycles occur mainly in cooler areas. Clutch size relative to body size is similar among species, but Erythrolamprus spp. seem to lay fewer eggs than other species, and Waglerophis merremii from southeastern and southern Brazil lay more eggs than other species. Newborn Erythrolamprus are larger than all other Xenodontini, which may be related to ophiophagy. As in many other snakes, adult females are larger than males, but both sexes attain maturity with a proportionally similar body size. The sexual size dimorphism index is generally lower in smaller bodied species, and combat may be absent in the tribe. Male reproductive cycles are less well studied but seem to be more conservative, being continuous in all species studied (W. merremii, Xenodon neuwiedii, and Liophis miliaris). Phylogeny has an important role in reproductive patterns but climate and life-history traits can also influence tropical and subptropical species.