HIV/AIDS is a major public health problem in Sub-Sahara Africa. Cytomegalovirus (CMV) has been found to be a major cause of morbidity and mortality in patients with Acquired Immunodeficiency Syndrome (AIDS). The virus has been reported to enhance HIV replication and accelerate the progression of HIV to AIDS. In Nigeria there is a dearth of information on the prevalence of Cytomegalovirus infection among HIV/AIDS patients. This study was designed to determine the prevalence rate as well as risk factors for CMV infection among HIV/AIDS patients in Ilorin, Nigeria. A cross sectional study was carried out among consecutively recruited HIV sero-positive patients attending the HAART clinic at U.I.T.H, Ilorin between October 2008 to September 2009. A volume of 5 ml blood sample was collected from each consenting participant as well as age and sex matched HIV sero-positive control group . The sera was assayed for CMV IgG/IgM using Enzyme Linked Immunosorbent Assay (ELISA). A semi-structured pre-tested questionnaire was also used to assess the risk factors for CMV infection among HIV sero-positive participants