The objective of this study was to examine whether hospital volumes of percutaneous transluminal coronary angioplasty (PTCA) are associated with adverse outcomes (coronary artery bypass graft surgery after PTCA and/or in-hospital mortality), post-PTCA length of stay (LOS), and hospital charges. Discharge data for 24,856 patients undergoing PTCA in 1989 from 110 California hospitals were analyzed. Regression analysis was used to adjust patient discharge data for risk factors. Actual and predicted adverse outcomes, LOS, and charges were compared for hospital volume categories (using 95% confidence intervals). Rates of adverse outcomes were significantly higher than expected in low-volume hospitals (< 201 PTCAs) and significantly lower than expected in high-volume hospitals (> 400 PTCAs). The results were similar for LOS and charges, although the results for charges were less conclusive. The associations of volumes and outcomes were generally consistent for both unadjusted and adjusted analyses, for patients with and without principal diagnoses of acute myocardial infarction, and using different methods and functional forms. Given this association between hospital volumes of PTCA and outcomes, future research should assess the underlying causes of this association and whether limiting the use of low-volume facilities would improve outcomes.