BACKGROUND: A potential role of testosterone among sex hormones has been hypothesized in identifying sex-related differences in the clinical consequences of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Due to the high global prevalence of hypogonadism, the relationship between hypogonadism and SARS-CoV-2 infection outcomes deserves an in-depth study. OBJECTIVE: The present study aimed to investigate the relationship of serum testosterone with other laboratory parameters on the prognosis of coronavirus disease-19 (COVID-19) in male patients with COVID-19 diagnosis. MATERIALS AND METHODS: This prospective cohort study included 358 male patients diagnosed with COVID-19 and 92 COVID-19 negative patients admitted to the urology outpatient clinics as a control group. The COVID-19 patients were divided into groups according to prognosis (mild-moderate and severe group), lung involvement in chest computed tomography (<50% and >50%), intensive care unit needs, and survival. RESULTS: The measured serum total testosterone level of the COVID-19 patients group was found to be significantly lower than that of the control group (median, 140 ng/dl; range, 0.21-328, 322 ng/dl; range, median, 125-674, p < 0.001, respectively). The serum TT levels were statistically significantly lower in severe COVID-19 patients compared to mild-moderate COVID-19 patients (median, 85.1 ng/dl; range, 0.21-532, median, 315 ng/dl; range, 0.88-486, p < 0.001, respectively), in COVID-19 patients in need of intensive care compared to COVID-19 patients who did not need intensive care (median, 64.0 ng/dl; range, 0.21-337, median, 286 ng/dl; range, 0.88-532 p < 0.001, respectively), and in COVID-19 patients who died compared to survivors (median, 82.9 ng/dl; range, 2.63-165, median, 166 ng/dl; range, 0.21-532, p < 0.001, respectively). DISCUSSION AND CONCLUSION: Our data are compatible with low TT levels playing a role on the pathogenesis of the disease in Covid-19 patients with poor prognosis and a mortal course and may guide clinicians in determining the clinical course of the disease.