Background: Infertility is one of the medical, social and psychological burdens in our society. Overt thyroid dysfunction is an accepted cause of female infertility. Its milder form, subclinical thyroid dysfunction, has also been implicated as a contributing factor to a disturbed reproductive function. Objective: This study aimed to determine the contribution of subclinical thyroid dysfunction (hypothyroidism and hyperthyroidism) to the burden of infertility and its associated risk factors at Olabisi Onabanjo University Teaching Hospital, Sagamu. Method: This analytical cross sectional study recruited 215 eligible women with infertility (primary and secondary) who presented for evaluation at the gynaecological clinic of Olabisi Onabanjo University Teaching Hospital, Sagamu. Venous blood samples were obtained and analyzed for serum Thyroid Stimulating Hormone, free triiodothyronine, free thyroxine and serum prolactin levels. Data analysis was carried out using SSPS version 23 and association between variables was determined using independent t-test, Chi square and ANOVA as appropriate. Multivariate analysis was done for associated risk factors. The level of statistically significance was set at p-value <0.05.