Background: Thyroid hormone disorders have an adverse effect on human spermatogenesis. Thyroid function has regulated by hypothalamic-pituitary-thyroid axis and thyroid stimulation hormone is a critical measurement of thyroid disorders. This study aimed to investigate the relationship between thyroid stimulating hormone and sperm parameters. Methods: This study has conducted 99 man who have visited RMC and Ojinmed IVF centers. Serum level of thyroid stimulating hormone (TSH) was measured by automated immunoassay analyzer (TOSOH AIA-360, Japan). Semen analysis was done in all the participants and evaluated by World Health Organization’s guidelines(2010). Results were calculated by SPSS 26 program. Results: The average age was 35.2±5.76. The mean serum TSH level was 1.37±0.57 and 1.85±1.16 normal subjects and spermatogenesis dysfunction group, respectively. Furthermore, serum TSH level and sperm parameters were significantly different between two groups (p<0.05). Logistical regression analysis showed that increased TSH level negatively affected the motility (r=-0.28; p<0.05) and progressive motility (r=-0.34;p<0.05) of sperm more than other parameters (r=-0.34; p=0.035). There was no correlation between serum TSH and other sperm parameters. We analyzed binary logistic regression for TSH with spermatogenesis dysfunction in case control groups. According to the analysis, elevation of serum TSH level increases the risk of spermatogenesis dysfunction by 5.0 times (OR=5.06, p<0.05). Conclusions Subclinical hypothyroidism adversely affect some sperm parameters, including motility and progressive motility. Subclinical hypothyroidism increases the risk of spermatogenesis dysfunction.