We studied the effect of diet and body weight on recurrence and death in 472 women diagnosed with early-stage breast cancer in 1982-1984. From Cos proportional hazards regression models we found that the strongest effects were observed in premenopausal women. For example, after accounting for disease stage and age, reported baseline consumption (times/day) of butter, margarine, and lard (risk ratio (RR) = 1.67; 95% confidence interval(CI) = 1.17-2,39) and beer (drinks/day) (RR = 1.58; 95% CI = 1.15-2.17) increased the risk of recurrence. There also appeared to be an increased risk associated with consumption of red meat, liver, and bacon. corresponding to about a doubling of risk for each time per day that foods in this category were consumed (RR = 1.931 95 % (CI = 0.89-4.15). Relative body weight increased risk at the rate of 9% (RR = 1.09; 95 % CI = 1.02-1.17) for each kg/m(2) equivalent to about 5.8 pounds for a woman 5'4" tall). For death, the results were similar, but relative weight was more strongly associated, increasing risk by 12% per kg/m(2) (RR = 1.12; 95% CI = 1.03-1.22).