Tamarind seed kernel powder (TSKP) is a cheap starchy biodegradable material that has not been tested before for its flocculating properties. Sedimentation of clay slurry has been studied using this material. We have also done experiments with chemical grade starch and its blends with TSKP and compared their performance with that of potash alum for sedimentation of the clay slurry. The sedimentation phenomenon showed constant and falling rate zones. Sedimentation velocity, mass flux and concentration have been calculated at different time intervals for all the flocculants. Among the three types of natural flocculants, starch showed the highest rate constant in the constant rate zone and TSKP offers faster sedimentation in the falling rate zone. Thus TSKP, starch and their blends are potentially attractive environmentally benign flocculants. A qualitative explanation of the flocculating property of TSKP has been given. © 2007.