This study was performed on 1480 productive records collected from private farm of Holstein Friesian cows. In addition, collection of 70 milk samples for the measurement of somatic cell count (SCC). This study aims to evaluate the effect of some non-genetic factors (days in milk (DIM), peak milk yield (PMY), dry period (DP), calving interval (CI), parity, and season of calving) on total milk yield (TMY). And studying the effect of 305-day milk yield (305-DMY), peak milk yield (PMY), days in milk (DIM), parity and season of calving on mastitis in Holstein Friesian cows. All data were analyzed by general linear model (GLM) using SAS software ver.9.1.3. The current results revealed that DIM and parity had a significant effect on TMY, where the highest milk yield was obtained when DIM were more than 357 days and in the 3rd lactation season. Season of calving showed a significant effect on mastitis disease, where the highest incidence of mastitis was recorded for spring calvers.