In order to establish the reference intervals (RIs) of peripheral blood lymphocyte subsets (PBL) in healthy adults in Lima (Peru), a cross-sectional study was conducted among blood donors taken in between 2011 and 2012. Based on the criteria obtained from the guidelines of the Clinical and Laboratory Standards Institute (CLSI C28-A3), 318 samples were processed, 61.9% (197/318) coming from male donors. For PBL count, a flow cytometer with a simple platform was used. The RIs are established for each PBL in adults based on sex with their respective reference limits and 90% confidence intervals. Differences were found in CD3+ percentage counts (p=0.001) and in CD3-CD56+ absolute (p=0.003) and percentage counts (p?0.001). The RIs found are different to those described in studies conducted in other countries due to the characteristics of the population and the study model.