To explore the possible endocrine-disrupting effect of cadmium (Cd), we have tested its role on very-low-density apolipoprotein II mRNA (apoVLDL II) expression by diethylstilbestrol (DES) in Japanese quail. Three-week-old immature male quail were intraperitoneally injected with DES (10mg/kg body wt and 24hrs before sacrifice) to induce apoVLDL II mRNA in the liver. The same birds were intraperitoneally injected with 0.001, 0.01, 0.1, 1 or 3 mg/kg body wt of CdCl2 at 48 hrs before DES injection. A reverse-transcription polymerase chain reaction (RT-PCR) was applied to quantify the mRNA level. We found that 0.1 mg/kg body wt of Cd injection contributed an additive effect in DES-stimulated apoVLDL II mRNA expression, whereas Cd injection above this level suppressed the effect. The present results suggest that Cd has biphasic effects on estrogen-dependent gene transcription, and 0.1 mg/kg body wt of Cd administration can mimic the estrogen functions in Japanese quail.