In the present study, the productive and reproductive performance of German Holstein Friesian dairy cows and subsequent generations born in Libya were evaluated.  The number of cows that had the first lactation record included in the study was 2094. Data were analyzed using REML to estimate factors affecting milk yield and reproductive traits. The model included: month, year of calving, management, generation, origin of sire as fixed effects and sire as random effect. In addition, age at first calving and lactation period included for milk yield traits as a covariate. Total milk yield was generally high (8409 Liters) and achieved with reproductive efficiency (110 days open) during Dutch management, and at the expense of the reproductive traits (161 days open) during Libyan Management. Management, calving year, calving month, age at first calving and lactation period had a significant effect on both milk yield and reproductive traits. In addition, milk yield and days open were affected by the Temperature Humidity Index (THI). A different trend of milk yield and days open was found during cold and hot seasons. However, Days open were more affected by the increased THI than high milk yield. Management plays important role to maintain high productivity with reproductive efficiency under heat stress conditions.