In this study, we compared the results of potency determination of recombinant human erythropoietin (rhEPO) obtained between 2010 and 2012 by the National Institute of Quality Control in Health (INCQS/Fiocruz), i.e., the National Control Laboratory (NCL), and by a manufacturer of rhEPO. In total, 47 different batches of commercially prepared rhEPO (alpha isoform) were analyzed. All results, including those of the control and warning limits, remained within the limits recommended by European Pharmacopoeia (Ph. Eur.). All relative error (RE) values were less than ± 30%, wh ereas most were approximately ± 20%. Applying the Bland-Altman plot, only two of 47 values remained outside the limits of agreement (LA). In addition, agreement of potency determination between INCQS and the manufacturer coefficient of variation of reproducibility (% CVR) was considered satisfactory. Taken together, our results demonstrate (i.) the potency assay of rhEPO performed at INCQS, is standardized and controlled, (ii.) the comparison of our results with those of the manufacturer, revealed an adequate inter-laboratory variation, and (iii.) the critical appraisal proposed here appears to be a feasible tool to assess the reproducibility of biological activity, providing additional information regarding monitoring and production consistency to manufacturers and NCLs.