A field experiment was conducted during winter months of 2003-04 and 2004-05 on a sandy clay loam black cotton soil to study the feasibility of using water hyacinth mulch for weed control and increasing productivity of potato cv. Kufri Chandramukhi. The weed control treatments consisted of control (no weed control measure), farmers practice (scrubbing the soil of inter rows space and earthing potato rows), water hyacinth mulch (HM), rice straw mulch (SM), metribuzin 250 g/ha as PE + HM, metribuzin 250 g/ha as PE + SM, metribuzin 500 g/ha as PE, and metribuzin 500 g/ha as PE + HM. Sprinkler irrigation was given immediately after planting, and flood irrigation was given during 3rd and 8th week after planting. Both rice straw and water hyacinth mulches controlled weed infestation throughout the growing period of potato, and no additional benefit of herbicide application in terms of weed control or tuber yield was noted in the mulched plots. The lowest tuber yield of 7.2 t/ha was recorded in control, it increased to 13.1, 20.8, 14.8, 21.1, 15.9, 13.0 and 21.4 t/ha respectively in the above mentioned treatments. It was concluded that water hyacinth mulch was superior to rice straw mulch in increasing potato yield in black cotton soil.