Objectives. To describe the prevalence and factors associated with the purchase of antimicrobials without a prescription (CASRM) in drugstore/pharmacy users according to the National Health User Satisfaction Survey (ENSUSALUD). Materials and Methods. A secondary analysis of ENSUSALUD 2016 was carried out; a study with two-stage probabilistic sampling in the Health Service Providers of the public and private subsector. The CASRM was evaluated by self-report. Crude (PR) and adjusted (PRa) prevalence ratios with 95% confidence intervals (95% CI) were estimated. Results. The study included 1.165 users who purchased antimicrobials. The mean age was 38.0 years (standard deviation: 13.4). The prevalence of CASRM was 53.4% (95% CI: 48.0-58.8). The prevalence of CASRM was higher in the highlands and jungle, respect to metropolitan Lima (PRa: 1,66; CI 95%: 1,37-2,02; y PRa: 1,61; CI 95%: 1,31-1,99; respectively); also was higher in pharmacy users compared to drugstore users (PRa: 1,25; CI 95%: 1,13-1,39). People with comprenhensive health insurance (SIS) had a lower prevalence of CASRM compared to people without insurance (PRa: 0,73; CI 95%: 0,60-0,88). The prevalence was lower if the antimicrobial was for the spouse (PRa: 0,65; CI 95%: 0,55-0,77) or child (PRa: 0,70; IC 95%: 0,52-0,93) compared to if it was buying for oneself. Conclusions. A 53.4% of drugstore/pharmacy users, who bought antimicrobials, did so without a doctor’s prescription. The prevalence of CASRM was higher in the highlands and jungle and in pharmacy users, as well as lower in those who had SIS and those who bought for their spouse or child. We suggest reinforcing the interventions, mainly regulatory and educational, in the highlands and in the jungle, as well as, in the population not affiliated to a health insurance.