A study was conducted to determine the effect of feeding concentrate diets containing graded levels of groundnut haulms on performance of Friesian x Bunaji cattle. In the first experiment twenty Friesian x Bunaji prepubertal heifers aged 14-16 months weighing 160-180kg were randomly divided into four groups and the groups were allotted four dietary treatments in a completely randomized design. The dietary treatments consisted of iso-nitrogenous concentrate mixtures in which groundnut haulms was included at 0, 25, 50 and 75% levels. The heifers were fed weighed quantity of concentrate mixture ad libitum and Andropogun gayanus (gamba) hay for 112 days. Prior to the commencement of the first experiment, a digestibility trial and nitrogen balance was carried out using sixteen bulls aged 12-18 months. The result showed that the digestibility of dry matter, organic matter, crude protein, crude fibre, ether extract, Neutral detergent fibre and Acid detergent fibre were significantly (P<0.05) higher in diets with 75% level of groundnut haulms. Increasing groundnut haulms level in concentrate diet up to 75% significantly (P<0.05) depressed both dry matter intake and gain of heifers. The result also showed that dry matter intake (DMI) was not significantly different (P>0.05) between heifers fed diet with 0, 25 and 50% groundnut haulms, but declined significantly (P<0.05) when groundnut haulms level reached 75%. The body weight and average daily gain of heifers fed concentrate diets containing 0 and 25% groundnut haulms were not significantly different (P>0.05); although they were higher (P<0.05) than for those in 50 and 75% groundnut levels. The result showed that rumen pH and Nitrogen were significantly(P<0.05) increased with the inclusion of groundnut haulms in concentrate diets. Feeding graded levels of groundnut haulms in concentrate diets of Friesian x Bunaji heifers significantly increased (P<0.05) serum glucose at 25 and 50% groundnut haulm. Concentrations of serum urea, creatinine and protein in heifers fed varying levels of groundnut haulms in concentrate diets slightly reduced, with increase in groundnut haulm levels in diet. There was a significant (P<0.05) increase in Red Blood Cell (RBC) with increase in the level of groundnut haulms in diet which was higher at 75% groundnut haulms level. The percentages of animals that attained puberty over the experimental period were 0, 40, 60 and 40% for 0, 25, 50 and 75% groundnut haulm levels respectively. The cost of concentrate diet both in Naira and in Naira per kilogram were reduced with increase in groundnut haulm levels in concentrate diet with Net benefit remaining positive across the treatments. In the second experiment, the effect of feeding concentrate diets containing varying levels of groundnut haulms on milk yield, milk compositions and cost- benefit analysis were examined. The animals were made of twenty Friesian x Bunaji cows at their first lactation periods. They were divided into four groups of five animals each, consisting of three postpartum and two prepartum each; and were randomly assigned to one each of the experimental diets in a completely randomized design. Results also show that there was significant difference (P<0.05) in dry matter intake (DMI) metabolic body weight, weight gain and average milk yield of lactating cows fed varying levels of groundnut haulms. At 25 and 75% levels of groundnut haulms in concentrate diets ADG were similar (P>0.05) but significantly (P<0.05) higher than their counterparts at 0 and 50% groundnut haulms levels. There was significant difference (P<0.05) in the total milk yield with those at 0% recording 557.9 litres, which were similar to cows fed 50% (538.8L) groundnut haulms in concentrate diets, but were however, significantly (P<0.05) higher than those at 25 (337.1L) and 75% (346.4L) groundnut haulms. Milk fat, lactose, Total solid and solid-not-fat differed significantly (P<0.05). Milk fat and Total solid decreased linearly with increase in groundnut haulms in concentrates diets of cows. Cost benefit analysis indicated that cows fed 50% groundnut haulms had better net benefit. It is concluded that, inclusion of groundnut haulms up to 50% in concentrate diet can improve reproductive performance of heifers, milk production and profit margins of lactating crossbred cows.