Chickens genetically selected for high incidence of articular gout and hyperuricemia were used to determine the site of defective uric acid (UA) transport in gout. The Sperber technique was used to compare the tubular secretion of preformed UA with the tubular secretion of UA formed within the tubular cells in gouty and nongouty chickens of the same strain. In gouty chickens, the tubular excretion ratio of preformed [14C]UA was 36% of the value obtained in nongouty chickens of the same strain, whereas the tubular excretion ratios of [14C]UA formed within the tubular cells from [14C]guanine were equal in the two types of chickens. This suggests that a UA transport is located at the peritubular membrane and that this mechanism is defective in gouty chickens. In addition, the transport of p-aminohippurate (PAH) was normal in gouty chickens, which suggests that the transport mechanism for UA is distinct from that for PAH.