To describe the age-sex pattern and socioeconomic differentials in causes of death among adults between the ages of 15 and 59 years in Zambia.Using data from the 2010-2012 Zambia sample vital registration with verbal autopsy survey, we calculated the percentage share of causes of death, the age-sex cause-specific death ratio, and cause-eliminated life expectancy at age 15.HIV/AIDS was the leading cause of death across all socioeconomic subgroups contributing 40.7% of total deaths during the study period. This was followed by deaths due to injury and accidents (11.2%). Cause-specific death ratios due to HIV/AIDS increased by age and peaked in the 35-to-39 age group, and were higher among females than males. The second leading cause of death was injuries and accidents for females and tuberculosis for males. The third leading cause of death was cardiovascular diseases for females and tuberculosis for males. Cause of death patterns varied notably by socioeconomic characteristics. Deaths attributable to non-communicable diseases were more evident in adults aged 45 to 59 years. Eliminating HIV/AIDS in Zambia as a cause of death could raise life expectancy at age 15 by 5.77 years for males and by 6.40 years for females.HIV/AIDS-related health programmes and interventions should be further supported and strengthened, as they would significantly contribute to the reduction of adult mortality in Zambia. This article is protected by copyright. All rights reserved.