Biathlon is a sport that combines cross-country skiing with rifle shooting. There is no well-described model of performance in this multi-sport event. This study aimed to identify the parameters influencing biathlon performance. In addition, the study aimed to search for a relationship between performance and measured blood parameters and to determine whether higher hemoglobin concentration [Hb] was associated with improved performance.Eighty-three male biathletes underwent pre-competition blood sampling in selected World Cup competitions. For all athletes (N=83) and for a subgroup of top-athletes (N=37), performance parameters identified were related to final standings by univariate and multiple regression analyses and, subsequently, to blood parameters measured on the same day. In athletes tested twice with different [Hb], performance corresponding to competitions with lower and higher [Hb] was compared.Among the parameters considered, the percent variation for both groups in best skiing time and percent of missed targets were independent determinants of performance (R2=0.853, 0.834, respectively) and were not correlated to blood parameters. In athletes with two samples, despite significantly different (Hb), no corresponding changes in performance were observed.In this study, the determinants of biathlon performance were identified. A relationship between measured blood parameters was not found, and the individual (Hb) variations observed were not associated with improved performance.