Aim: The aim was to determine the pattern and predictors of medication use among adults in the communities of Southwestern Nigeria. Methods: A cross-sectional study was conducted among adults selected by multi-stage sampling from Oyo State communities. The questionnaires, adapted from the WHO Students’ Drug Use Questionnaire and previous studies, were pretested and interviewer-administered. The respondents’ socio-demographic characteristics, the pattern of medication use, prescribers and sources of drug acquisition were obtained. Binary logistic regression was used to determine the predictor of medications used. Results: Of the 999 respondents, 501 resided in rural communities while 498 dwelled in urban areas. The mean (±SD) age of the respondents was 38±15years. The median (range)% prevalence of medication use were: lifetime use, 58.2(17.7-81.0), current use, 31.2(8.9-65.9) and past use, 20.3(9.2-28.9). Medications were mainly obtained from patent medicine stores, median (range%), 71(65-80). The commonly used drugs were paracetamol,626(67.6), Nonsteroidal anti-inflammatory drugs, 174(18.8), artemether/lumefantrine, 422(68.2), Ampicillin/cloxacillin, 220(48.6), and chlorpheniramine, 59(40.4). Factors predictive of current medication use, AOR (95% CI) were: antimalarial [male, 0.7(0.5, 0.9)]; antibacterial [male, 0.6(0.4-0.9)]; analgesics [married, 1.5(1.1-2.2), presence of health facilities, 0.5(0.3-0.7), and shorter distance to health facility, 1.5(1.1-2.1)]. Conclusion: Antimalarials, antibacterial and analgesics were commonly used and inappropriately obtained by adults in Southwestern Nigeria. Factors predictive of current medication use were gender, marital status, the presence of health facilities and distance to health facilities. There is a need for more extensive countrywide medication use studies and enlightenment programs to ensure the appropriate use of medications.