The effects of acetochlor on the mortality, growth and reproduction of two nematode species were assessed. The LC50 values for Caenorhabditis elegans and Pristionchus pacificus were 1,296 and 210.7 mg/L at 24 h, and 540.0 and 126.4 mg/L at 48 h exposure, respectively. In three succession generations, reproductive capacity was more sensitive in P. pacificus than in C. elegans. Moreover, the sublethal test endpoint of final length was more sensitive with P. pacificus. This study suggested that acetochlor had no long-term effects on C. elegans at lower concentrations. The higher concentrations of acetochlor (from 40 to 160 mg/L) revealed sublethal toxicity to the two tested species, with P. pacificus being more sensitive than C. elegans.