HIV testing among persons with tuberculosis (TB) results in high-yield identification of persons infected with HIV. To evaluate differences in HIV testing among children versus adults with TB in Vietnam, we collected and analyzed age-disaggregated facility and aggregated provincial data from the National Tuberculosis Program. HIV testing was incompletely documented for >70% of children, whereas adult testing data were >90% complete. Standardized training of personnel for universal HIV testing and documentation for children with TB could improve HIV case-detection and permit linking of children with HIV to antiretroviral treatment to prevent morbidity and mortality.