Abstract: AIMTo investigate the antagonistic effect of curcumin on DNA damage in immune organs in vivo induced by sodium arsenite (NaAsO₂). METHODSMale ICR mice were given curcumin 2, 20 and 200 mg·kg^-1 for 14 days before treatment with sc injection of NaAsO₂ at the dose of 10 mg·kg^-1. After injection, the mice were sacrificed at the end of 1 and 3 hours. DNA strand breaks were detected in the splenocyte, thymocyte and marrow cells through single cell gel electrophoresis (SCGE). RESULTSCurcumin was shown to inhibit DNA strand breaks induced by NaAsO₂ in a dose-dependent manner. It was found that curcumin 20 and 200 mg·kg^-1 could reduce the DNA strand breaks induced by NaAsO₂ 1 hour after treatment in cells from spleen. The percent of “comet” cell was decreased. Curcumin 20 and 200 mg·kg^-1 treatment was shown to reduce the DNA strand breaks induced by NaAsO₂ three hours after treatment in cells from thymus and bone marrow. CONCLUSIONCurcumin can prevent the DNA strand breaks induced by NaAsO₂ in cells from spleen, thymus and bone marrow in vivo.