Background: The purpose of this study was to evaluate levels of NitricOxide (NO) and testosterone (T) in seminal plasma of men with normal and abnormal semen analysis (SA),and determine if correlations between seminal plasma NO, T and sperm quality exists. Material/Methods:Subjects consisted of 9 men with a normal SA and 24 men with abnormality of at least one parameter inthe SA. Seminal plasma NO was analyzed using chemiluminescence, and testosterone by immunoassay. Results:Men with normal and abnormal SA were of comparable age and had no significant medical history. Subjectswith abnormal semen had significant impairment of at least one parameter of their SA. Mean seminal plasmaT levels were significantly lower in subjects with abnormal SA. In subjects with abnormal SA, there wasa significant positive correlation between seminal plasma NO and sperm morphology, as well as a positivetrend between seminal plasma NO and T. In all subjects there was a highly significant positive correlationbetween sperm morphology and seminal plasma T. Conclusions: NO and testosterone are detectable in seminalplasma and are potentially involved in spermatogenesis. Low levels of seminal plasma NO and T are associatedwith defects in sperm morphology.

Keywords: Cell Count, Nitric Oxide - analysis, Radioimmunoassay, Semen - chemistry, Sperm Motility - physiology, Spermatozoa - physiology, Testosterone - analysis