The application of strychnine (S) is limiteddue to its toxicity, but its derivative strychnine nitrogen oxide (SNO) is used widely in clinical practice.We here employedZebrafish embryos to investigate and compare the developmental toxicity induced by S and SNO.Embryo malformation was observed in the embryos exposed to S at 200 μmol· L-1.When SNO concentration was increased to 1 mmol· L-1, scoliolosis and pericardial edema could be seen in some embryos.Results from fluorescence microscopy and flow cytometryanalysis showed that S at 200 μmol· L-1 induced apoptosis,wheras apoptotic rate in SNO-treated group (200 iμmol·L-1) was much lower than that in the S group.RT-PCR analysis showed that p53 mRNA expression and the ratio of Bax/Bcl-2 inthe S groupwere significantly alteredcompared with the control group (P <0.05).Moreover, Bax mRNA expressions in both S and SNO group were significantly different from that in the control group (P<0.01).These results could lead to the conclusion thatSNOhad low toxicity than strychnine in zebrafish embryos.