Pseudoboini snakes of the genera Clelia and Boiruna are apparently rare in nature and certainly rare in collections. This work presents data on body size, reproduction and abundance of five Brazilian species of these genera, in the largest collection of snakes in Latin America, the Instituto Butantan. Despite scarcity of data, follicular cycle seems to be continuous in most species, except Clelia rustica, which occurs in highlands. Females are largerthan males in all species, and fecundity is low when compared to other pseudoboini. Abundance is very low for all species even considering 100 years of collecting, and it is decreasing in recent decades when compared to other snakes (Bothrops jararaca, Oxyrhopus guibei, O. clathratus, Philodryas patagoniensis, Sibynomorphus mikanii, and Spilotes pullatus). The studied species present at least five traits of commonly threatened species and require more attention in researches and conservation policies.