During mammalian spermatogenesis, the chromatin structure undergoes substantial condensation. The key role in this process is played by protamines 1 and 2 (PRM1, PRM2). We attempted to compare the levels of PRM1 and PRM2 transcripts in mature spermatozoa of normospermic and asthenozoospermic men. Human ejaculates from normozoospermic (n=70) and asthenozoospermic (n=100) donors were purified by centrifugation through discontinuous Percoll density gradient. RNA was isolated from spermatozoa according to the Chomczyñski and Sacchi method, treated with DNase I, and reverse-transcribed into cDNA. Using reverse transcription and real-time quantitative polymerase chain reaction analysis, we found a reduction in the levels of PRM1 and PRM2 transcripts in spermatozoa from asthenozoospermic men, as compared to controls (P<0.001). Our findings indicate that a reduction in contents of PRM1 and PRM2 transcripts in spermatozoa may be linked with asthenozoospermia.