It has been suggested that an HIV diagnosis may increase the likelihood of mental disorders among infected individuals and that the progression of HIV may be hastened by mental disorders like anxiety and depression. Therefore, a brief screening measure, with good sensitivity/specificity for psychiatric diagnoses that could be given to HIV-infected individuals would be useful. We assessed the validity of the K-10, using the MINI International Neuropsychiatric Interview as the gold standard, in a sample of 429 HIV-infected adults enrolled in HIV care and treatment services near Cape Town, South Africa. There was significant agreement between the K-10 and the MINI-defined depressive and anxiety disorders. A receiver operating characteristic (ROC) curve analysis indicated that the K-10 showed agreeable sensitivity and specificity in detecting depression (area under the ROC curve, 0.77), generalized anxiety disorder (0.78), and posttraumatic stress disorder (PTSD) (0.77). The K-10 may be a useful screening measure for detecting mood and anxiety disorders, including PTSD, in patients with HIV/AIDS.