Results.\p=m-\Therewas a significant decrease in the rates of in-hospital mortality (P=.04), emergency bypass surgery (P<.001), Ml (P=.001), and major complica- tions (defined as one or more of these outcomes; P<.001) with increasing cardiac catheterization laboratory volume. After adjustment for case mix using multivariable analysis, these associations persisted, although the association with mortality was no longer statistically significant. There was no significant difference in outcomes in laboratories performing at least 200 vs fewer than 200 procedures per year, the currently recommended minimum laboratory volume (odds ratio (OR) for major complications, 0.81; 95% confidence interval (CI), 0.53 to 1.25). However, a statis- tically significant decrease in major complications was observed in laboratories performing more than 400 procedures per year (adjusted OR, 0.66; 95% CI, 0.46 to 0.96; P=.03; and OR, 0.54; 95% CI, 0.38 to 0.78; P=.001) when laboratories per- forming 400 through 599 procedures and at least 600 procedures per year, respectively, are compared with those performing fewer than 200 per year. Conclusions.\p=m-\Aninverse association between cardiac catheterization labora- tory procedure volume and major complications during PTCA exists independent of differences in patients' risk profiles. Our data suggest that the currently recom- mended minimum laboratory volume may be too low to distinguish higher-risk from lower-risk laboratories.