INTRODUCTION: As a continuous decline in semen concentration has been reported, the concept of male infertility has gained increased attention. Although several surveys of semen quality have been conducted in young men in general, no study has reported only on newlywed men. AIM: The aim of this study was to evaluate semen quality and assess its characteristics in newlywed men. METHODS: This study included 564 men visiting our hospital or clinic for fertility screening just before their wedding or as newlywed men. Based on the World Health Organization criteria, the rates of men who did not have a semen volume of ≥1.5 mL, a sperm concentration of ≥15 million/mL, and a sperm motility rate of ≥40% were calculated. The characteristics of the poor semen findings group with any 1 of the 3 items of semen volume, sperm concentration, or sperm motility rate not reaching the reference value were evaluated. MAIN OUTCOME MEASURE: Independent factors, which are involved in the poor semen findings group, were evaluated. RESULTS: The poor findings in semen volume, sperm concentration, and sperm motility were found in 11.0%, 9.2%, and 10.6%, respectively. The poor semen findings group included 143 men (25.4%) with any 1 of the 3 items not reaching the reference value. As compared to the normal group, age and body mass index were significantly higher, testicular volume was significantly smaller, and blood gamma-glutamyltransferase and fasting blood sugar levels were significantly higher in the poor semen findings group. Logistic multivariate analysis, including symptom questionnaire scores, blood biochemistry items, and endocrinological items, showed 3 independent factors were involved in the poor semen findings group: age, luteinizing hormone, and erection (Erection Hardness Score). CONCLUSION: It was clarified that even among men beginning their attempts at pregnancy, semen findings were poor and erectile dysfunction was involved in poor semen quality in one-quarter of the men. Tsujimura A, Hiramatsu I, Nagashima Y, et al. Erectile Dysfunction is Predictive Symptom for Poor Semen in Newlywed Men in Japan. Sex Med 2019;8:21-29.