Data on erectile dysfunction (ED) in Nigeria are limited. The study determined the influence of socio-demographic characteristics on ED prevalence in Ilorin, Nigeria. A sample of 399 married men aged 20-70 years was taken. They responded to a questionnaire adapted to reflect the local cultures. Data on socio-demographic characteristics, current use of penile erectile enhancers and erectile function were obtained. Erectile function was assessed using the abridged five-item version of the International Index of Erectile Function (IIEF-5). Presence of ED was defined as IIEF-5 score of <21. Descriptive and test statistics were applied to the quantitative data. The results revealed ED prevalence of 46.9% with 34.3, 9.8 and 2.8% having mild, moderate and severe ED, respectively. Men aged 40-64 years, reported severe ED from 9.1 to 36.4%. Yoruba ethnic group had the highest ED prevalence. Of the variables, age, length of marriage and spousal status were significantly associated and correlated with ED (P<0.05), while ethnicity, religion and age at first marriage were not (P>0.05). With an aging population, ED may become a significant health problem in similar environments in Nigeria.