Pinworm infestation (enterobiasis, syn. oxyuriasis), though not usually dangerous, remains one of the commonest parasitic infections seen by the family physician. Particularly prevalent in the pediatric age group, pinworms also infect adults; in both groups the commonest symptom is pruritus ani. Detailed descriptions of history, life cycle, and epidemiology are given. In addition to hygienic measures useful in treatment, the particulars of drug therapy are also outlined.