The study on the chemical composition of the seeds of one of the most popularly known and popularly consumed tropical plant, Gnetum africana (afang) has been carried out by analyzing samples of the plant seeds collected from some plantations located within Akwa Ibom State (South Eastern Nigeria) for chemical Composition. The proximate, elemental and toxicant composition of the seeds (Gnetum africana) were determined by analyzing samples of the identified seeds for their carbohydrate, protein, lipid, ash, fibre, moisture and caloric value (proximate composition), iron, zinc, lead, potassium, sodium, magnesium and calcium (mineral compositon) and tannin, hydrocyanic acid, oxalate and phytic acid (toxicant composition) using recommended method of analysis. The result of the analysis shows that the percentage moisture content, crude protein, crude fat, crude fibre, ash content and carbohydrate of this seeds are 31.60%, 17.50%, 3.15%, 0.80%, 1.20% and 87.62% respectively while its caloric value is 448.83kcal/100g. The percentage sodium, potassium, calcium, magnesium, iron, zinc and lead content of the seed were 15.57, 38.56, 7.01, 5.48, 1.50, 1.50, 1.07 and 0.03 respectively while its toxicant content were 540mg/100g, 100.74mg/100g, 209.00mg/100g and 238.26mg/100g for hydrocyanic acid, tannin, oxalate and phytic acid respectively. The proximate, mineral and toxicant composition of the seeds were also compare with values reported in literature for other edible vegetable and the results show that the seeds are poor source of essential elements compared with other vegetable seeds. The antinutritional content of the seeds were very high when compare to values reported for other vegetables. Based on the result of the present study, it has been found that afang seeds are rich in proximate composition (when compare with other edible vegetables). Their low mineral content and their high toxicant content therefore suggest that these seeds should be properly processed before consuming them and its consumption should be supplemented with other food whose elemental content are high.