To investigate whether BCG vaccination can prevent endometrial implantation in a rat model. Forty sexually mature virgin Wistar-Albino rats weighing 185-215 g were randomly assigned (double-blind) to two groups. The first group (n = 20) were injected with BCG 3 weeks before endometrial implantation to the eye. The second group (n = 20) with BCG not injected before endometrial implantation was the control. Photobiomicroscopy observation was done weekly and 6 weeks post endometrial implantation all eyes were investigated histologically.