OBJECTIVE To study the effects of butyl benzyl phthalate on neurobehavioral development of rats. METHODS Levels of 0 (control), 0.05%, 0.25%, and 0.75% butyl benzyl phthalate (BBP) was given in the diet from 4 weeks of age of female F0 generation to 6 weeks of age of F1 generation in Wistar rats, including the period of the female F0 generation's mating, gestation and lactation and the F1 generation's growth and development. Selected parameters of neurobehavioral development were observed in F1 generation. RESULTS (1)For the male F(1) generation, surface righting at postnatal (PND) 4 th day was significantly delayed in the low-dose group (P < 0.05) (scoring: 56 vs 61), cliff avoidance at PND 7 was significantly depressed in the high-dose group (P < 0.05) (scoring: 41), air righting at PND 14 was significantly depressed in all treatment groups (P < 0.05). In open field test, low- and high-dose groups moved more than control group (P < 0.05). In Morris water maze test, the escape latency was significantly delayed in the low-dose group at the 5th day of the 5 days' place navigation task (P < 0.05). (2) For the female F1 generation, there were no differences among groups in any parameter in the experiment (P > 0.05). CONCLUSION BBP may affect the neurobehavioral development only in male rats in the F1 generation.