This study investigated the effectiveness of combining cloprostenol (Cl) and progesterone (Pg) injections for oestrous synchronization in female rats. A comprehensive series of experiments was conducted to explore the impact of hormonal injections on subsequent reproductive behaviour. The study involved dividing rats into distinct groups, with each group subjected to specific injections of either Cl, Pg, or their combinations. We observed a 100% conception efficiency within the first day after the last Cl injection in the Cl + Pg + Cl group. This finding underscores the remarkable effectiveness of the employed protocol, resulting in a rapid initiation of pregnancy in a substantial number of female rats on the same day.