High proportions of self-medication were similar in both pharmacies, despite the differences in monthly income and educational level. This differs with findings in other studies. One comparative study in Brazil documented a higher prevalence of self-medication in higher socio-economic classes versus lower socio-economic classes; higher socio-economic patients paid out of pocket for their medications and lower socio-economic patients had free access to medication. In this Brazilian study, paying for medications was a positive factor associated to self-medication [26]. Another study in Mexico showed that low socio-economic status and lower educational level were positively associated to self-medication [11]. Practices in self- medication and their relation to socio-economic status have been defined in these settings, but to our knowledge this has not been previously established in Guatemala. Our findings suggest that self-medication with antibiotics in this urban Guatemala City setting is high despite differences in monthly income and educational level.