Ketoprofen is a nonsteroidal anti-inflammatory drug with analgesic, anti-inflammatory, and antipyretic activities. This study aimed to evaluate the potential embryotoxic effects of ketoprofen, on chicken embryos using the in-ovo method. The LD50 value, embryotoxic dose limit, and macroscopic findings in the embryos were examined. A totalof 420fertilized chicken eggs were randomly divided into 2 groups and both groups were placed in the incubator at the same time. Group-1 (n = 210): The group treated on the 14th day of embryonic development. and group-2 (n = 210): Group-1 and group-2 were divided into 7 subunits, each consisting of 30 fertilized eggs. Different doses of ketoprofen (100, 50, 25, 12.5, and 6.25 mg/kg) were injected into the air-sacs of fertilized eggs in both groups. At the end of the 21-day incubation period, embryotoxicity was evaluated in all groups. As a result, a statistically significant difference in mortality increase was detected between the control group and the 100 mg/kg and 50 mg/kg groups following the 7th day injection (P < 0.05). No statistically significant differences were found in the other groups (P > 0.05). Similarly, no statistically significant difference was detected among all experimental groups as a result of the 14th day injection (P > 0.05). In conclusion, the findings obtained in this study demonstrate that ketoprofencauses a dose-dependent embryotoxic effect in the early embryonic period, but this effect is not evident in the late period.