The modulation of common carp, Cyprinus carpio L. phagocytic cells by Di-n-butyl phthalate (DBP) and Di-2-ethylhexyl phthalate (DEHP) were analyzed in vitro. Carp head kidney leucocytes were cultured in a RPMI 1640 medium containing DBP or DEHP at concentration of 1-1000 nM and the production of superoxide anion was measured via the in vitro reduction of nitroblue tetrazolium (NBT). Macrophages incubated with 100 up to 1000 nM of DBP showed an increase in their production of superoxide anion in comparison with the control macrophages which, were cultured without DBP. DEHP also increased the production of superoxide anion in phagocytic cells from carp kidneys. Phagocytic cells treated with 10 and 100 ng of DEHP showed increased phagocytic activity. DBP and DEHP also significantly increased the production of nitric oxide in carp macrophages. These results showed that DBP and DEHP modulate the function of phagocytic cells in vitro.