The Toxicity of Congo red to earthworm, Megascolex konkanensis was studied. The toxicity was concentration dependent and the percent survival decreased with increasing concentration in water and soil. The concentration of congored which was sub lethal under normoxic condition became lethal under hypoxic condition. In soil, with increase in water content, a decreasing trend in LC50 value was observed. The severity of behavioral and morphological changes increased with increasing concentration of congored in water and soil.