Background: Sexual dysfunction is common, but often under-recognised, in people with schizophrenia. Many antipsychotic drugs are known to cause prolactin elevation, and it is often assumed that sexual dysfunction is a consequence of prolactin elevation. We investigated the relationship between sexual function and serum concentrations of prolactin and testosterone in men receiving regular long-acting depot injections of antipsychotic medication. Methods: Twenty-two men attending a community depot clinic participated. A structured interview was used to collect information about sexual function, and serum prolactin and testosterone concentrations were measured. Results: Sexual dysfunction was common, with 73% of men reporting problems in at least one area of sexual function. Six men had elevated serum prolactin and one had reduced serum testosterone. Antipsychotic drug dose was positively correlated with serum prolactin and negatively correlated with serum testosterone, but there was no association between serum prolactin or testosterone concentrations and any measure of sexual dysfunction. Conclusion: Sexual dysfunction is a major problem for men living with chronic schizophrenia, but our results suggest that it is not directly attributable to elevated prolactin or reduced testosterone concentrations.