Crambe meal was compared to a combination of sunflower and soybean meal as a protein supplement for mature beef cows in two experiments. In Exp. 1, cows (n = 80, average BW 651+/-14.4 kg) were fed crambe meal at 9.86% of dry matter intake (DMI) during the last trimester of gestation. No differences (P < .05) were detected due to treatment for cow weight, condition score, thyroid hormones, calf birth weight, or calving interval. In Exp. 2, cows (n = 100, average BW 566+/-6.82 kg) were fed crambe meal at 7.44% of DMI during the last trimester of gestation and at 8.33% of DMI during early lactation (53+/-6 d of lactation). Gains were greater during gestation (P = .09) and throughout the supplementation period (P = .06), and days to first estrus were reduced (P < .01) for cows fed crambe meal. During lactation, serum triiodothyronine (T3) concentrations did not decline as much (P = .03) in cows fed crambe meal as in cows fed sunflower-soybean meal-based supplements. No differences (P > .10) were apparent for condition score, birth weight, calf growth rate, weaning weight, thyroid hormones during gestation, or calving interval. These data indicate that crambe meal fed at the levels used in this experiment can be used as a protein supplement for beef cows without negatively affecting cows' performance.