Purpose-Use the meta-analytic approach to examine the effects of aerobic exercise on highdensity lipoprotein two cholesterol (HDL 2 -C) in adults.Study sources-(1) Computerized literature searches; (2) cross-referencing from retrieved articles; (3) hand-searching; and (4) expert review of our reference list.Study selection-(1) Randomized controlled trials; (2) aerobic exercise ≥8 weeks; (3) adults ≥18 years of age; (4) studies published in journal, dissertation, or master's thesis format; (5) studies published in the English-language between January 1, 1955 and January 1, 2003; and (6) assessment of HDL 2 -C in the fasting state.Data abstraction-All coding conducted by both authors, independent of each other. Discrepancies were resolved by consensus.Results-Nineteen randomized controlled trials representing 20 HDL 2 -C outcomes from 984 males and females (516 exercise, 468 control) were pooled for analysis. Using random-effects modeling and bootstrap confidence intervals (BCI), a statistically significant increase of approximately 11% was observed for HDL 2 -C (X̄ ± S.E.M., 2.6±0.9 mg/dl, 95% BCI, 1.0-4.4 mg/dl). With each study deleted from the model once, results remained statistically significant. Increases in HDL 2 -C were independent of decreases in body weight, body mass index (kg/m 2 ), and percent body fat.Conclusion-Aerobic exercise increases HDL 2 -C in adults.