The effect of adding mango, guava pulp, total milk protein powder, skim milk powder, storage period and fat ratio on Chemical composition was investigated. Results revealed that the addition of mango and guava pulp to skim milk increased the acidity, total solids (T.S), reducing sugars (R.S), non reducing sugars (N.R.S) and viscosity of the final product. However it had a negligible effect on the total protein (T.P) and non protein nitrogen (N.P.N) of the final product. The increase in fat ratio caused an increase in total solids, total protein, non protein nitrogen, pH and viscosity. However decreased the acidity and it had no effect on reducing sugars (R.S) and non reducing sugars (N.R.S). The fortification of mango and guava - flavoured cow's skim milk beverages with total milk protein powder (retentate) and skim milk powder increased T.S, T.P, N.P.N, acidity and viscosity. On the other hand that fortification decreased the reducing sugars (R.S) and pH. Pasteurized beverages had a marked increase on R.S, N.P.N, acidity and viscosity, and a decrease in N.R.S and pH after storage on refrigerator condition up to 2 weeks. However, the changes in T.S and T.P during storage were slight.