Background and Objectives: Guava (Psidium guajava) belongs to the family Myrtaceae. It has been cultivated in Nigeria one of the most common fruits in Nigeria. It has become popular because of its availability almost throughout the year. The objective of this study is to evaluate the nutritional and vitamin contents of the flesh of the local and improved guava species. Materials and Methods: Proximate components were determined using the AOAC method for the moisture, ash, crude lipid, nitrogen content (crude protein) and Carbohydrate. Vitamins A, B1, B2, B3, B6 and B12 were analyzed using standard methods. Results: The result showed that moisture and carbohydrate content of the improved white guava flesh is low compared with the local white guava species (9.8825 and 14.4015%) and (56.378 and 62.802%), respectively. The ash, fat, fibre and protein content of the improved white guava flesh are high compared with the local guava species (11.25 and 5.15%), (5.55 and 1.335%), (6.6145 and 6.5865%) and (10.325 and 8.225%). Improved White guava flesh is relatively low in Vitamin A, vitamin B3, vitamin B6 and vitamin C compared to local white guava flesh, while the local white guava flesh is relatively poor in vitamin B1, vitamin B2 and vitamin E compared to improved white guava flesh. Conclusion: The present findings suggest guava flesh as a considerable source of nutrients in the diet and may have health and economic benefits due to its vitamins, and nutritional composition.