The daily activity of nine dipsadid snakes from southeastern Brazil was characterized using captive specimens monitored by a digital video system. Six species (Apostolepis assimilis, Erythrolamprus aesculapii, Liophis miliaris, Philodryas patagoniensis, Thamnodynastes strigatus, and Tomodon dorsatus) were diurnal and three species (Atractus pantostictus, Oxyrhopus guibei and Sibynomorphus mikanii) were nocturnal. The daily activity pattern was highly variable among species. However, intra-specific variation in both period and activity pattern was observed in some of the studied species. Although activity period is usually conservative within lineages, our results indicate that activity pattern might be strongly influenced by biotic or abiotic factors.