In this study, embryotoxic effects of five commercially available dental alloys were investigated by using fertilized hens' eggs. One sample of each alloy was conditioned in one of the conditioning media, physiological saline (PS), 0.1 M phosphate-buffered saline (PBS, pH 7.4), and 0.1 M protein (3% bovine serum albumin, BSA) containing PBS (pH 6.8), respectively. The test solutions were injected into the fertilized hen's eggs via air sac at the beginning of the incubation. Various concentrations of a highly embryotoxic substance, AFB1, was also used as positive control test material. Mortality of the AFB1 treatment groups increased with increasing concentrations of AFB1 and the mortality values were significantly (p < 0.05) higher than those of the controls and eluent injected groups. The eluents of five commercially available dental alloys tested in the study did not have significant embryotoxic effects. Cu- and Pd-containing alloys displayed relatively high but statistically insignificant embryotoxic effects. Chick embryo might be used in determination of the embryotoxic effects of the dental alloys with its several advantages. Nevertheless, the test should be further standardized and new methods such as micronucleus test showing possible genotoxic effects of the materials should be used. © 2004 Wiley Periodicals, Inc.