In buffaloes, an optimal BCS at calving time improves reproductive efficiency (Baruselli et al., 2001) therefore shortening the calving/conception period and lowering the number of services/conception. In buffalo cows in negative energy balance a delayed ovulation and a reduced percentage of large follicles were found (Campanile et al., 2001). In buffaloes naturally mated protein degradability in the rumen did not influence reproductive activity (Campanile et al., 2003). It is possible that, independently of the Blood Area (BU), a lower diffusion of ammonia occurs in the uterus, reducing the detrimental effect on reproductive efficiency. The aim in the present study was to determine the influence of BCS, urea e ammonia blood levels on conception rate in Italian Mediterranean buffaloes synchronised and mated by AI in mid-winter which coincided with transition to the seasonal nadir in reproductive activity.