Pinworm or thread worm infection could not be easily treat because its recurrence is very common. Very small worm and only mebendazole 100 mg single dose is enough to treat but dose repetition is needed to all members of the family, may be 3 to 6 times may be needed. A female worm contains 10,000 to 50,000 eggs and unlike the other intestinal helminthes does not lay eggs in the lumen of the intestine rather they lay eggs in the perianal skin and the eggs then spread on the night cloths, bed and on the floor. Eggs can be easily spread by air to nose and mouth of members of the family and deglutinated. So recurrence is very common. Clean the floor with swabs not dry cleaner. I used ivermectin, recurrence is less.