BACKGROUND: Aerobic exercise is recommended for improving lipoprotein and lipid levels which at less than their optimal levels are risk factors for cardiovascular disease. Evidence seems lacking for the effectiveness of exercise in reducing these levels, possibly due to small sizes in studies. We concluded a meta-analysis of the studies to examine the effects of aerobic exercise on lipids and lipoproteins in adult men. METHODS: Studies were retrieved via computerized literature searches, cross-referencing from retrieved articles, hand-searching, and expert review of our reference list. Inclusion criteria were randomized controlled trials, aerobic exercise ≥8 weeks, adult men ≥18 years of age, studies published in journal, dissertation, or master's thesis format, studies published in the English-language between January 1, 1955 and January 1, 2003, and assessment of one or more of the following lipids and lipoproteins: total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDLC), and triglycerides (TG). All coding was conducted by both authors, independent of each other. Discrepancies were resolved by consensus. RESULTS: Forty-nine randomized controlled trials representing up to 67 outcomes from 2,990 men (1,741 exercise, 1,249 control) were pooled for analysis. Using random-effects modeling, statistically significant improvements were observed for TC, HDL-C and TG, and a trend for decreases was observed for LDL-C. Changes were equivalent to improvements of 2% for TC and HDL-C, 3% of LDL-C, and 9% for TG. CONCLUSIONS: Aerobic exercise reduces TC and TG and increases HDL-C in men 18 years of age and older.