Results of vitamin C content of Irish and sweet potato tubers are as presented in Table 2. Raw Irish potato contains 56.47 mg/100 ml vitamin C. The highest loss of 37.34 mg/100 ml (68.90%) was observed when boiled while frying resulted to a loss of 30.44 mg/100 ml (53.90%). The vitamin C content obtained for Irish potato is in agreement with Babalola et al. (2010), who obtained losses of 63.43% and 54.60% respectively when the Irish potatoes were boiled and fried. The result presented in Table 2 for sweet potato also revealed the same trend of loss as that obtained for Irish potato. Raw sweet potato contained 70.69 mg/100 ml vitamin C. Boiling in water produced a loss of 51.16 mg/100 ml (72.37%) while frying produced a loss of 43.05 mg/100 ml (60.90%). Babalola et al. (2010), failed to evaluate how boiling and frying best retained minerals. They also obtained losses of 63.43% and 54.60% respectively, when sweet potatoes were boiled and fried. The values obtained for sweet potato is higher when compared with the values reported by Sinder et al. (1973), who obtained losses of 65% and 57% respectively when the potatoes were boiled and fried. Aidoo (1966), also obtained losses of 58% and 50% respectively when Irish potatoes were subjected to the same processing method as above, and losses of 93% and 85% respectively were encountered when yam was subjected to the same treatment as potatoes. These losses were higher than those obtained for Irish and sweet potatoes. The vitamin C loss in Irish and sweet potatoes could be due to the effect of heating as well as leaching into the boiling water. Duke (1983), and Gernah and Ajir (2007) reported that heating (especially boiling in open pots) can cause huge losses of vitamin C.