Objective: The aim of this study is to determine the possible embryotoxic effects of propofol, a general anaesthetic agent that is commonly used in clinical practice, on peripheral blood lymphocytes using enzyme histochemical techniques. Methods: For this purpose, 430 laying hen fertile eggs were used for this study. The eggs were divided into 5 groups as control, solvent-control (saline), 2.5 mg kg−1 propofol, 12.5 mg kg−1 propofol, and 37.5 mg kg−1 propofol, and injections were performed via the air sac just before the incubation. The peripheral blood alpha naphthyl acetate esterase and acid phosphatase-positive lymphocyte ratios were determined on the hatching day. Results: No statistically significant difference was found between both alpha naphthyl acetate esterase and acid phosphatase-positive lymphocyte ratios of the control and solvent-control groups. However, when compared with the control and solvent-control groups, statistically significant decreases were observed in the peripheral blood alpha naphthyl acetate esterase and acid phosphatase-positive lymphocyte ratios of the chicks from the propofol-injected groups. Besides, the difference between 2.5 mg kg−1 and 12.5 mg kg−1 propofol groups is not significant, whereas the difference between these 2 groups and the 37.5 mg kg−1 propofol group was statistically significant (P < .05). Conclusions: It was concluded that propofol given to fertilised chicken eggs just before incubation caused significant decreases in both the peripheral blood alpha naphthyl acetate esterase and acid phosphatase-positive lymphocyte ratios.