Infertility is a growing issue globally, particularly in industrialized cultures, affecting 13%-18% of couples of reproductive ages. In recent years, numerous studies have aimed to identify prognostic factors for infertility and abnormal semen analysis. To date, no study has examined the relationship between the number of infertile siblings and abnormal sperm parameters. This study aims to investigate whether the number of infertile siblings can be considered a prognostic factor for abnormal sperm parameters. Semen samples were collected from the male partners of couples experiencing infertility issues. Study participants completed a questionnaire detailing demographic information including age and family history of infertility. Each participant provided two semen samples, with a minimum 15-day interval between collections. Sperm concentration, motility, and morphology were assessed for each sample. Clinical investigators conducted physical examinations, using an orchidometer to measure testicular size. The number of infertile brothers and testis volume were prognostic factors for abnormal sperm count (OR = 1.374, p-value = 0.03; OR = 0.786, p-value < 0.001; respectively) and abnormal motility (OR = 1.514, p-value = 0.018; OR = 26.74, p-value < 0.001, respectively). There was no significant association between the percentage of abnormal morphology of sperm cells and the mentioned prognostic factors. The optimal cut-off point of the number of infertile brothers for both abnormal sperm count and abnormal sperm motility was one. It is recommended that males with at least one infertile brother, undergo sperm analysis to identify individuals at risk of infertility.