Schizophrenia is a chronic mental illness which poses a tremendous burden on the families, caregivers and the society. The purpose of this paper is to provide an updated review of the epidemiology of schizophrenia with a special attention to the clinically important risk factors such as drug abuse, hormonal factors and the new advances in genetic research. The authors reviewed the literature with a special focus to the recent papers published from January 1970 to present. The prevalence of schizophrenia varied by ten-fold and the incidence of schizophrenia varied by five-fold among different studies. Significant advances in genetic research and DNA technology have been achieved over the past two decades and suggested substantial genetic etiology of schizophrenia. Extensive studies have been done with many variations in the prevalence, incidence and risk factors of schizophrenia among different studies.