A study in gout of the incidence of diagnosis from 1971 to 1975 and of the prevalence at 31 December 1975 was carried out in a representative general practice sample comprising 64 practices and a population numbering 1 in 145 of the total population of Great Britain. The results show an annual incidence in Great Britain from 1971 to 1975 varying from 0.25 to 0.35 per 1000 and an overall prevalence at 31 December 1975 of 2.6 per 1000. The prevalence in England was found to be significantly greater than in the rest of Great Britain and that in Wales to be significantly greater than in Scotland. In 10% of the cases the gout was believed to be secondary, with induction by diuretics being the most frequent cause. The prevalence of primary gout was estimated to be 2.3 per 1000.