This study was carried out to evaluate the current performance of dairy cattle at ASAS and Kitulo farms in the Southern Highlands of Tanzania. The objective was to assess the effects of genetic and non-genetic factors on lactation and reproductive performance, calf mortality rate, longevity traits and constraints affecting performance of dairy animals. Ayrshire and Friesian cows were involved in the study. Data were analysed using General Linear Models procedure of Statistical Analysis System (SAS). Average ages at first calving (AFC) at ASAS farm were 1059.5±19.41 and 1105.7±12.99 days for Ayrshires and Friesians, respectively. Breed and calving period significantly (P < 0.05) influenced AFC. At Kitulo farm AFC was 1151.7±9.63 days. Both parity and period of calving significantly (P < 0.001) influenced CI. Mean calving intervals (CI) at ASAS farms were 410.8±8.1 and 423.4±6.8 days for Ayrshire and Friesian cows, respectively. At Kitulo farm mean CI was 421.6±1.43 days. Mean lactation milk yields (LMY), lactation lengths (LL) and dry periods (DP) at the ASAS farm were 2696.8±75.4kg, 305.8±5.7 and 92.9±2.6 days, and 3000.1±62.9kg, 318.7±4.8 and 96.3±2.2 days for Ayrshires and Friesians, respectively. Breed (P < 0.001), parity (P < 0.001) and period of calving (P < 0.05) significantly influenced LMY and DP. At Kitulo farm mean LMY, LL and DP were 2608.3±24.0 kg, 322.3±1.4 and 91.2±0.52 days. Only period had a significant (P < 0.01) effect on LL. Overall abortion, stillbirth, pre-weaning and post- weaning mortality rates were 4.8, 3.7, 6.5 and 11.0% for ASAS farm. Corresponding rates at Kitulo farm were 11.2, 7.6, 12.1 and 13.0%. Mean lifetime milk production at ASAS farm for Ayrshires and Friesians were 11 303.6 and 13 517.5 kg while at Kitulo farm it was 13 481.2 kg. Management improvement including testing andiii vaccination of heifers against brucellosis and rehabilitation of infrastructures is therefore recommended.