Pressure leaching of scheelite floatation tailings containing 6.55% of WO₃was done under various conditions. To obtain more than 90% extraction, four equivalents of soda ash as decomposer and two hours leaching at 190℃ was necessary. Soda ash was the best decomposing agent and the addition of caustic soda was effective to shorten the leaching time. Effect of pulp concentration and pH was briefly examined.