Hepatic cells apoptosis induced by olaquindox in common carp, Cyprinus carpio, were studied. The test was conducted for 30 days, with dose of 200mg·kg-1 feed. Terminal deoxynucleotidy transferase mediated dUTP-Biotin nick-end labeling （TUNEL）, electronic microscopic and flow cytometry were performed to analyze apoptosis. The result showed that hepatic cells apoptosis were indentified under light microscope with TUNEL staining; chromatin condensation, chromosal clumping and margination, and apoptotic bodies were observed under electronic microscope; and sub-G1 PEAK （AP peak） in hepatic cells could be detected by flow cytometric method. The apoptotic rate measured by flow cytomtry increased with dye-poison time, on the 7th,14th,20th,25th and 30th day, the apoptotic rate was 2.05%, 6.25%, 9.49%, 13.31% and 17.44% respectively.
