Antioxidant activities of some species of Mangnifera indica seed kernel (sucking mango, bush mango and opiororo mango) extracts were studied. The antioxidants capacities of the mango seed extracts were compared to some known synthetic antioxidant. Results obtained showed that the three different species of Mangnifera indica seed kernel which have 30.24+0.030%, 21.11+0.010% and 15.14+0.020% for sucking, bush and opiororo mangoes respectively had a lower scavenging capacity compared to the synthetic positive control standard (vitamin C) which recorded 32.57+0.001% in DPPH radical scavenging assay. Mangnifera indica specie B (bush mango) had the highest scavenging capacity (66.76+0.014%) compared to the synthetic positive control BHT (64.40+0.020%) in the reducing power determination assay. Mangnifera indica specie B (bush mango) and specie C (opiororo mango) had higher scavenging capacities of 14.64+0.031% and 14.29+0.019% for hydrogen peroxide scavenging capacity compared to synthetic sodium pyruvate which has 13.01+0.009%. Proximate composition of three varieties of mango seeds was also determined. The percentage moisture, ash crude fat, crude fibre, protein and carbohydrate contents was determined using A.O.A.C. method. Opiororo mango and Sucking mango had similar values for moisture content (8.00%) while Bush mango had comparable value of 8.05%. The ash content ranged between 0.40 - 1.80% and Bush mango had the highest value of 1.80±0.03%. The fat content was observed to be between 14.29±0.05% and 27.14±0.01% with sucking mango having the highest fat content (27.14±0.01%). Bush mango and Opiororo mango had similar values for crude fibre (49.50%) while sucking mango had comparable value of 49.00±0.03%. The crude protein ranged between 9.26 - 14.27%. This study suggests that the seeds may be nutritionally potent with appreciable high levels of nutrients and energy which can be incorporated into feed/food.