Our objective was to document change in stent usage in a single practice over time and to study "off-label" compared to Food and Drug Administration (FDA)-approved indications. Although only two intracoronary stents have been approved by the FDA, the relatively limited approved indications do not account for the dramatic increase in stent implantation. This increase has important implications for patient health care delivery. This study of stent usage in a single center over a 36-mo period included all patients treated with coronary stents at the Mayo Clinic from January 1993-December 1995, and evaluated the relative difference in frequency between "off-label" and FDA-approved indications for implantation. During the 36-mo period of study, 3,614 interventional procedures were done and one or more stents were placed in 25.4% of patients. The proportion of patients receiving stents increased throughout this time: during the first 6-mo period, stents were placed in 6.2% of procedures; during the last 6-mo period, stents were placed in 46.3% of procedures, an eightfold increase. During the final 6 mo, an unapproved device or an unapproved indication for an approved device constituted 59.4% of all stent procedures. In addition, use of the non-FDA-approved adjunctive treatment regimen without warfarin increased from 2.9% in the first 6-mo period of observation to 82.7% in the last 6 mo. The use of stents increased strikingly over a 36-mo period, from 6% to 46% of all procedures. The majority of implantations were performed either for an "off-label" unapproved indication or with an unapproved device.