Introduction: Peru ranks next to last in the number of transfusions of units of red blood cells per 1000 inhabitants in 17 countries of America. Objective: To determine the frequency of voluntary blood donation and its associated factors in medical interns in 12 cities of Peru, 2016. Material and Methods: An analytical cross-sectional study was conducted. The study population consisted of 1229 medical interns from 35 hospital sites distributed in 12 cities. The final sample was made up of 637 interns (51.8 % of the total). To do this, mixed effect logistic regression models were used for the conglomerates formed by the hospital in which the student performed the internship. Adjusted odds ratios (ORa) and 95 % confidence intervals were calculated. Results: The results show that 40.2 % of medical interns donated blood voluntarily at least once in their lifetime and 7.1 % did it at least three times in their lifetime. In the adjusted analyzes, being over 25 years old compared to be under 24 years old (ORa: 2.00, 95 % CI: 1.05 - 3.83) was associated with history of one blood donation; while being female (ORa: 0.15, 95 % CI: 0.05 - 0.43) was inversely associated with history of at least three blood donations. Conclusion: Although four in ten interns have donated blood at least once, less than one in ten have donated blood at least three times. The older age was associated with having donated blood voluntarily at least once. Women were less likely to have donated blood at least three times.