The Ficus capensis Thunb leaves are affected by some foliar diseases, which could reduce the nutrient benefits from these leaves. This study aimed at isolation and characterization of fungal pathogens associated with the plant's foliar diseases, analysis of the proximate and phytochemical composition of healthy and diseased fruits and leaves. The effect of isolated fungal species on these proximate and phytochemical contents of leaves was also investigated. Hendersonula sp., Didymeria conferta, Rhizopus stolonifer and Fusarium oxysporium were isolated and characterized as fungi associated with the leaves. Proximate analysis revealed the presence of protein, carbohydrate, lipid, ash, fiber, and moisture. Mineral nutrient analysis revealed the presence of copper, zinc, lead, manganese, magnesium, potassium, sodium, calcium, while that of anti-nutrients revealed saponin, alkaloid, flavonoid, tannin and cyanogenic glycoside, both in the diseased and the healthy leaves and fruits of the plant. The values of the food nutrients and minerals in healthy leaves were significantly different from those of the infected fruits and leaves, with the value of non-nutrients in infected leaves were higher than those in health ones. The non-nutrients in the infected leaves were higher than those in the healthy leaves and fruits of the plants, while the proximate and mineral composition of the supposedly healthy leaves was greater than those of diseased leaves.