Introduction: Basic life support (BLS) are a group of maneuvers that constitute a fundamental tool to save lives. Therefore, knowledge about BLS has to be part of the curriculum in medical schools. Objective: Evaluate the knowledge level about BLS and evaluate its associated socio-educational factors, in medical students from nine Peruvian universities. Material and methods: We carried out a cross-sectional multicenter study in 2013 and 2014. We included undergraduate medical students from nine universities in eight regions or Peru. We measured the knowledge about BLS using a validated questionnaire, which was based in American Heart Association Guidelines (2010); adequate knowledge was defined as a minimum proportion of 50% of correct answers. We estimate adjusted prevalence ratios using generalized linear models. Results: We included 1,564 students, 13% of the students had an adequate knowledge, and average score was 6.3 ± 3.2 (range: 0-16). Adequate knowledge was associated with attending semesters that belong to academic stage of clinical sciences (p = 0.02; aPR: 1.82; CI: 95%: 1.11-2.98) and having received a previous BLS course (p > 0.01; aPR: 2.96; CI: 95%: 2.18-4.01); adjusted by age, sex, having received a previous injections and first aids courses, and to manifest the desire to be trained in practical BLS. Conclusion: A low proportion of students have an adequate knowledge level about BLS in this population.