Prostate cancer occurs more frequently among older males and such elderly individuals often have chronic underlying disorders for which various drugs are administered for treatment. The levels of prostate-specific antigen (PSA), a widely used prostate cancer marker, are influenced by a number of drugs, such as non-steroidal anti-inflammatory drugs and statins. In the present study, the drugs prescribed to patients on a repeat prescription collected at the pharmacy of the Gifu Pharmaceutical University (Gifu, Japan) were examined for their effects on the levels of PSA expression in prostate cancer LNCaP cells. Among the 14 drugs investigated, betamethasone, an agonist of the glucocorticoid receptor, was found to increase the levels of PSA mRNA expression in the LNCaP cells. This betamethasone-induced expression was mediated, at least in part, through androgen receptor (AR) transcriptional activation. Dexamethasone, a typical agonist of the glucocorticoid receptor, was also found to stimulate the AR transcriptional activity, however, to a lesser extent than betamethasone. Therefore, it would be interesting to examine in future studies whether the serum PSA levels in prostate cancer patients are influenced by betamethasone.