In order to investigate the effect of different levels of niacin supplementation on growth, nutrient utilization, their balance and blood biochemical profile, 15 male buffalo calves (9-10 months of age, $88.4{\pm}4.37kg$ average body weight) were divided into 3 equal groups each of 5 calves, following a completely randomized design, and fed individually for 120 days with wheat straw and concentrate mixture to meet their nutrient requirements. In addition calves were supplemented with 0 ppm (control, group I), 100 ppm (group II) and 200 ppm (group III) niacin. After 90 days of experimental feeding a metabolism trial was conducted to estimate the digestibility of nutrients and their balance. Fortnightly body weights were recorded to assess their growth rate and blood was collected from the jugular vein at day 0 and subsequently at 30-day intervals from all the experimental buffalo calves to study blood biochemical parameters. Results showed that intake and digestibility of dry matter, organic matter, crude protein, ether extract, total carbohydrates, neutral detergent fibre, acid detergent fibre, cellulose and hemicelluloses were statistically similar in the 3 groups. Buffalo calves in all three groups were in positive nitrogen, calcium and phosphorus balance, without showing any significant effect of the treatments. Dry matter, crude protein, digestible crude protein and total digestible nutrient intake ($g/d/kgW^{0.75}$) were similar in the control and niacin supplemented groups. Digestible crude protein (%) and total digestible nutrients (%) in the ration of the 3 groups were 8.07, 7.99, 7.92 and 56.70, 56.63, 56.74, respectively, and were comparable among the groups. The average daily gain (g) in-group II (567.50) was not significantly (p>0.05) higher than group I (500.0) and group III (510.0). Blood biochemical constituents (glucose, total protein, albumin, globulin, urea-N, insulin) showed no significant effect of niacin supplementation. However, serum cholesterol (mg/100 ml) was significantly (p<0.01) lower in the 200 ppm niacin-supplemented group than in the control and 100 ppm niacin-supplemented groups. It can be concluded that supplementation of niacin at 100 and 200 ppm in the diet of buffalo calves had no significant beneficial effect on their growth and nutrient utilization.