With rubella and, until recently, measles highly endemic in Uganda, health personnel are at risk of these vaccine-preventable diseases and a source of transmission to patients. Measles and rubella serology (IgG) and history of exposure and vaccination were determined among 311 health care workers in a nationwide study. All tested positive for measles IgG, whereas 49.2% reported having been vaccinated. Rubella antibodies were present in 98.1% of personnel; 3.2% of women of child-bearing age were still susceptible. Increasing age and longer duration of service increased the risk of rubella infection. A national policy on health worker protection should include immunisation against vaccine-preventable diseases upon entry to training.