A study of 801 school going children in Karachi revealed that 717.of them gave history of passing worms. On administration of single oral dose of Pyrantal pamoate, 787. of those with history of passing worms expelled, while 597.of the children who gave no history of passing worms, expelled them Pyrantal pamoate is a safe ant-helminthic and can be successfully used in situations where facilities for laboratory investigations do not exist.