Crotalaria are species that have been of great use in agricultural production systems, due to their potential for nitrogen fixation, reduction of nematodes and good soil coverage. However, there are difficulties in the management of weeds throughout the cycle of these crops, since there are no registered herbicides. The objective was to evaluate the selectivity effect of post-emergent herbicides in Crotalaria spectabilis and Crotalaria ochroleuca. Two experiments were conducted, one with C. spectabilis and the other with C. ochroleuca, and in the agricultural year 2014/15, the experimental design used was in randomized blocks, with four replications. The treatments consisted of the application of ten post-emergence herbicides (piritiobaque-sodium doses 22,4 and 42 g a.i. ha-1, mesotrione 72 g g a.i. ha-1, ethoxysulfuron 12 and 24 g a.i. ha-1, bentazone 600 g a.i. ha-1, 2,4-D 564 g a.i. ha-1, atrazine 1,250 g a.i. ha-1, flumiclorac-pentyl 30 g a.i. ha-1 and imazetrapir 30 g a.i. ha-1), and a control treatment. Phytotoxicity, height, plant stand, number of leaves per plant, flowering and dry mass of the aerial part were evaluated. It was concluded that imazetapyr (T4), bentazone (T7), flumiclorac-pentyl (T9) and in both crotalaria and piritiobaque-sodium species in the two doses (T2 and T3) in Crotalaria spectabilis, were the herbicides that promoted the lowest levels phytotoxicity, as well as low or no interference with height, plant stand, number of leaves and dry mass of the aerial part, indicating possible selectivity.