Abstract This study investigates the phytochemical composition, proximate analysis and vitamin content of Tetracarpidium conophorum (black walnut) seed. Standard procedures were used for the analyses, the result of the phytochemical composition of the walnut seed reveals the presence of the following which increase in this order; tannins < cyanides < terpenoids < saponins < steroids < cardiac glycosides < flavonoids < alkaloids. Proximate composition of the walnut seed was found to be; protein 18.42 ± 0.04%, ash 2.86 ± 0.02%, fat 4.88 ± 0.04% and fibre 6.6 ± 0.08%, Moisture 32.63 ± 0.02% and carbohydrate 34.59 ± 0.02%. The seeds also contain some appreciable amount of vitamins; vitamin A 9.64 ± 0.01 mg/100g, vitamin C 6.98 ± 0.02 mg/100g, vitamin E 96.42 ± 0.02. The B-group vitamins were also found in trace amounts. The presence of these bioactive and nutritive compounds in the seed has made it a veritable source for good health conditions.