Objective: The authors tested the effect of blood sampling (skin versus venous puncture) on some biochemical and hematological blood parameters in athletes to answer whether skin puncture could be used as a substitute for venous puncture. Design: Comparative study of 2 methods of blood samples collection. Setting: The blood was collected in the same athletes at 3 different moments of the preparatory training phase. Participants: Fourteen male indoor soccer players (22 +/- 1 years old) and 7 female handball players (18 +/- 1 years old) participated. Main Outcome Measurement: Blood was collected in heparin and K(3)EDTA by Vacutainer BD or Microvette Sarstedt system for biochemical and hematological analyses, respectively. Results: There were no significant statistical differences between the 2 methods for the values of creatine kinase, urea, creatinine, lymphocytes, and platelets. The other hematological analyzes and uric acid exhibited significant higher values in skin blood, although they were all within the normal expected range. A high degree of correlation was observed between the 2 techniques for all parameters. Conclusions: Skin puncture is a reliable, easy, accurate, and less invasive sampling method for assessing hematological and some biochemical parameters in athletes, respecting that blood samples should always be obtained from the same site, especially in follow-up studies.165418421