Sexual dysfunction is more prevalent in psychotic patients than in the nonpsychotic population. The objective of this study was to identify correlations between serum prolactin levels, testosterone levels and erectile dysfunction in patients with first‐episode psychosis (n = 40) compared to age‐matched healthy controls (n = 40). All subjects underwent clinical evaluation, international index of erectile function (IIEF5) score assessment and measurement of serum prolactin and total testosterone levels. In first‐episode psychotic patients, the IIEF‐5 score and total testosterone levels were significantly lower, while serum prolactin levels were higher. We concluded that men with first‐episode psychosis are at an increased risk for development of erectile dysfunction, and increased duration of untreated psychosis leads to a higher incidence of erectile dysfunction and hyperprolactinemia.