Background Self-medication is a common behavior in the general population, specially among those suffering from chronic pain. Aim: To study the prevalence and characteristics of self medication. Subjects and Methods: Aiming to know the prevalence and features of self medication, a structured interview was applied to 272 out of 419 individuals from the general population, that reported musculoskeletal symptoms. Results: Sixty five percent of those interviewed recognised self medication. No gender differences were observed and there was a trend towards a higher frequency of self medication among older individuals. The frequency of self-medication was higher in low socioeconomic groups, subjects with long lasting pain, those with more severe pain and among subjects with a previous prescription. The drugs more frequently used were dipyrone, piroxicam and aspirin. The average daily piroxicam dose reported was 27 mg. Self medication was not associated with the labor condition of the subjects or the time of occurrence of symptoms. Conclusions: Self medication is a frequent behavior, particularly among low socio-economic groups and those with long lasting and more severe pain (Rev Méd Chile 2001; 129: 647-52