Objective: To explore the relationships between granulysin and semen parameters in varicocele patients either fertile or infertile and control subjects with unknown reproductive potential. Design: a case control comparative study Setting: Benha university hospital. Patient(s): Twenty-five infertile varicocele patients, twenty-five fertile varicocele patients and twenty-five normal, fertile controls. Methods: This small case controlled study assessed seminal concentrations of granulysin in infertile VC patients (n = 25), fertile VC patients (n = 25) and normal fertile controls males. Following a detailed medical history and examination, participants meeting the inclusion criteria were entered for data analysis. Semen samples were collected and assayed for granulysin after standard semen analysis Result(s): seminal granulysin levels were elevated in infertile VC patients than fertile VC patients and controls. It was negatively correlated with sperm count and testicular volume, while it was positively correlated with VC grade and duration Conclusion(s): The increased level of seminal granulysin in infertile patients with varicocele is possibly involved in varicocele-associated infertility through its negative influence on spermatogenesis.