Cassava bacterial blight, first observed in Nigeria ih 1971, caused an estimated loss of 25 million naira in cassava production in East Central State of Nigeria in 1976. Results in the present study showed that yield was reduced from 10.61 million t/ha at severity class 1.77 to 6.22 million t/ha at severity 2.01. Increasing K content of the leaves by K-fertilization from 0 kg K2O/ha to 180 kg K2O/ha in a soil with 0.25% N, 20.08 ppm P, 2.85 m.e. Ca/100 g, 1.17 m.e. Mg/100 g and 0.20 m.e. K/100 g tended to reduce the severity and enhance the yield. The main effects of N- and P-fertilization at rates up to 60 and 30 kg/ha respectively were not significant with respect to root yield. Highest root yields were obtained with the fertilizer level of 30 kg N/ha, 15 kg P2Os/ha and 180 kg K2O/ha.