The pandemic of HIV/AIDS is one of the defining medical and public health issues of all time and ranks among the greatest infectious disease scourges in history. There has been an increasing global drive for scaling up of HIV prevention and treatment services among vulnerable groups. Though people with severe mental disorders constitute part of these groups, there is paucity of studies assessing the risk among them, especially in low and middle income settings. This study was therefore aimed at assessing the level of HIV knowledge, risk behaviours and associated factors among patients with schizophrenia to help inform the nature and level of intervention needed to significantly reduce the risk of HIV infection among them. Cross sectional study design was used for the study. Adult patients with diagnosis of schizophrenia were recruited through the outpatient clinic of Neuropsychiatric Hospital, Aro, Abeokuta. Diagnosis was validated using the schizophrenia module of the MINI plus. HIV Knowledge Questionnaire (HIV- KQ-18), HIV risk screening instrument as well as Positive and Negative Syndrome Scale of Schizophrenia (PANSS) were used to assess HIV knowledge, HIV risk behaviour and psychopathology respectively. Majority of the participants (56.8%) had low level of knowledge of HIV while 33.7% reported at least one HIV risk behaviour in the previous 6 months. Sex trading was more common among women, while 5.8% of participants reported having sexual partners who were into Men having Sex with Men (MSM) .There was significant relationship between level of HIV knowledge and HIV risk behaviour (p=0.003). However, there were no significant relationships between HIV risk behaviours and either socio-demographic characteristics or psychopathology. There is both low level of HIV knowledge and high HIV risk behaviours among patients with schizophrenia. It is therefore important that HIV risk assessment should be included in the routine psychiatric evaluation of this group of patients. Furthermore, there is need for policy that will ensure the scaling up of HIV prevention and treatment services in mental health settings in the country.