Laqqan M, et al. - Researchers designed a current study to assess if there was a variation in the status of global DNA methylation among the study groups and to evaluate their influence on the protamine expression level and human semen parameters. They collected 200 semen samples from males (50 proved fertile, 60 normospermia and 90 oligospermia) with an average age of 34.9 ± 4.3 years. The DNA and RNA were separated from purified spermatozoa; then, ELISA and qPCR were used to determine the status of global sperm DNA methylation and protamine expression level respectively. In addition, as well as they assess the sperm chromatin decondensation and sperm DNA fragmentation. Among the study groups, global sperm DNA methylation and the protamine 1 and protamine 2 expression level were found significantly. In comparison with the proved fertile group with fold change, down-regulation has been found in the protamine 1 and protamine 2 expression levels in the oligospermia group. The study suggests that perhaps the protamine expression level was affected by alteration in global DNA methylation and might be leading to abnormalities in human semen parameters.