The reference group analyzed the samples from the participating laboratories. Statistic features such as mean, median, standard deviation, minimal and maximal value, first and third quartile were assessed for every examined parameter. Z-score index was used to compare the differences between assessed laboratories and the reference laboratory. The acceptable Z-score range was +/-1. Results: Average concentration in the reference group was 43 mln/ml, while in the assessed laboratories (L) it was between 31 (L4) and 72.5 mln/ml (L1). Z-score for concentration analysis in three laboratories exceeded +/-1 (2.51 for L1, 1.42 for L2 and -1.02 for L4). In the analysis of the first sample for progressive motility, the reference group received 59%, while the values of participating laboratories varied from 42,5% (L1) to 80% (L4). Most of the centers achieved Z-score within the normal range, except for L1 and L4 (-1.48 and 1.88 respectively). The reference value for the second sample for motility was 33%. The received results ranged between 22% (L6) and 48% (L7). Z-score was -1.27 for L6 and 1.73 for L7, while the results of other laboratories were close to the reference group. Reference morphology for the first sample was 3%. The results sent by the participating laboratories varied from 2% (L2 and L3) to 72.7% (L8). Assessment of the first sample of sperm morphology resulted in significant differences in 4 laboratories: Z-score of 12.41 for L8, 2.54 for L5, 2.19 for L4 and 1.12 for L1. The reference morphology for the second sample was 1%, while the sent results ranged from 0% (L3) to 45.8% (L8). Z-score for the second sample was 5.69 for L8, and 3.07 for L4 and 1.18 for L5. Conclusions: 1) Significant differences between the laboratories in the obtained results of the analysis of sperm parameters, especially the morphology, were found during the external quality assessment of the semen analysis. 2) Taking part in EQAP provides laboratories with information which procedures and stages ought to be improved in order to increase the reliability of semen results.