The effect of di(2-ethylheksyl) phthalate (DEHP) on LH secretion in Prussian carp (Carassius auratus gibelio B.) and common carp (Cyprinus carpio L.) was evaluated. In the in vitro study, pituitary cells were cultured in the presence of DEHP. In the in vivo study fish were exposed to DEHP in water. DEHP slightly stimulated the spontaneous LH secretion, but it inhibited the sGnRHa-stimulated release. It seems that DEHP can influence the reproduction of fish by disturbing LH secretion.