Two Chinese populations over age 15 were surveyed as to the point prevalence of "incapacitating" headaches in an urban population of 1,525 persons and a rural one of 1,203. Personal interviews were carried out by a team of instructed interviewers; there was 100% cooperation. In both populations, prevalence in women was twice that in men except in the urban population in the youngest age group. Prevalence in the urban was almost exactly twice that of the rural population, with the highest figure occurring in traders.