Background: In February 1999 we encountered our first patient with rhab domyolysis treated with the combination of bezafibrate and simvastatin, and realized the need to prevent adverse reactions when combining bezafibrate with HMG-CoA reductase inhibitors. In early March 1999 bezafibrate labeling for adverse reactions was revised, prohibiting combination therapy with HMG-CoA reductase inhibitors when serum creatinin levels reached>1.5 mg/dl. We have subsequently investigated the influences of the bezafibrate labeling changes on prescription trends for HMG-CoA reductase in hibitors combined with bezafibrate.Methods: We identified all patients within the period May 1998 to March 1999 who had visited the cardiovascular department at Kansai Medical University Hospital (Osaka, Japan) and received bezafibrate with HMG-CoA reductase inhibitors, as recorded in the computerized prescription data.Results: The number of patients who had received bezafibrate with HMG-CoA reductase inhibitors was 97 (mean age 60.2±9.9 years), of whom 78 had previously received HMG-CoA reductase inhibitors prior to additional bezafibrate. In these 78 patients, the mean serum total cholesterol and triglyceride levels after adding bezafibrate had decreased by 5.5±17.6% and 33.4±33.0%, respectively. For patients receiving both lipid-lowering agents, the results of periodic measurement of serum creatinine and creatin kinase levels were considered insufficient, and these parameters had not been measured for more than 4 months in 57% and 76% of the cases, respectively. Of the 97 patients, either bezafibrate or HMG-CoA reductase inhibitors had been withdrawn from treatment in 15 patients (15.5%) by the end of March 1999. By the end of March 2000, one year after the bezafibrate labeling changes, no patient had commenced the combina tion therapy of both lipid-lowering agents, and within that year 37 patients (38.1%) discontinued treatment with either bezafibrate or HMG-CoA reductase inhibitors (total 52 patients, 53.6%).Conclusions: The hospital pharmacy caution issued regarding the prevention of adverse reactions is seen as contributing to the decrease by approximately one-half the number of patients receiving bezafibrate with HMG-CoA reductase inhibitors. In the near future, the combination therapy of bezafibrate and HMG-CoA reductase inhibitors can be eliminated by selective usage, and by the establishment of an appropriate dosage setting for, HMG-CoA reductase inhibitors.