Chronic prostatitis/chronic pelvic pain syndrome CP/CPPS is a rather common condition and in recent years many studies have shown contradictory results regarding its impact on semen quality. This prospective cohort study set out to investigate how CP/CPPS affected the parameters of semen in a prospective cohort of patients compared with the WHO 2021 reference group. From 2013 to 2022, a total of 1071 patients with suspicion of CP/CPPS received a comprehensive andrological examination. Complete semen analysis was carried out in compliance with WHO 2010 guidelines, comparing every study population semen variable to the WHO 2021 reference group (n~3500). All evaluated semen parameters had median values that fell within a normal range. Nonetheless, approximately 25% of patients had values for each semen variable that were lower than the WHO reference group's fifth percentile. In particular, bacteriospermia was associated with a negative impact on semen volume. This is the largest study that compares all standard semen parameters in patients suffering from CP/CPPS to WHO 2021 reference values. It provides evidence of an impairment of conventional semen parameters.