The course of HIV/AIDS in children has been transformed from an acute to a chronic one with the advent of Anti-Retroviral Therapy. The aim of this study was to determine the prevalence and pattern of psychiatric morbidity in HIV-infected children and adolescents between 6 and 18 years of age and the relationship between their socio-demographic factors, immune suppression and psychiatric morbidity. The study was conducted at a paediatric HIV clinic in Nairobi, between February and April 2010. One hundred and sixty-two HIV-infected children and adolescents aged between 6 and 18 years and their guardians were interviewed. Seventy-nine (48.8%) of the study participants were found to have psychiatric morbidity. The most prevalent Diagnostic Statistical Manual, 4th Edition TR psychiatric disorders were: Major depression (17.8%), Social phobia (12.8%), Oppositional Defiant Disorder (12.1%) and Attention Deficit Hyperactivity Disorder (12.1%). Twenty-five per cent of the study participants had more than one psychiatric disorder. The prevalence of psychiatric morbidity in HIV-infected children is higher than that found in children in the general population. There is therefore a need to integrate psychiatric services into the routine care of HIV-infected children.