This paper attempts to establish a relationship between the undrained strength and plasticity index of tropical clays. Its theoretical basis lies with the previous works of Skempton and Northey  and Atkinson and Bransby . The data obtained from independent laboratory tests on so some clay samples sourced from several actual project locations in Eastern Nigeria, were subjected to statistical least squares regression analysis after the samples had been grouped into CL, CI and CH using the Unified System of Soil Classification. The derived regression equations are shown to have high correlation coefficients thereby proving their viability. These equations can be used to estimate the undrained strength of clays encountered in Eastern Nigeria in lieu of the very expensive triaxial compression tests.