The influence of parathyroid extract on calcium and phosphorus levels in the blood and urine of two species of iguanid lizards has been investigated. The Desert Iguana, Dipsosaurus dorsalis, and the Mesquite lizard, Sceloporus grammicus , were injected daily with parathyroid extract for 1 week. Urine pellets were excreted within 5–7 days. Urinary mineral levels were determined as concentration and total clearance per pellet. After PTE treatment, hypercalcemia was observed in D. dorsalis , while bone citric acid was slightly, but not significantly, elevated. Both D. dorsalis and S. grammicus responded to repetitive doses of PTE by elevated urine calcium and phosphorus titers. Plasma phosphorus, studied only in PTE-treated D. dorsalis , showed no change from normal. A marked decrease in urine pellet weight was noted in PTE-treated lizards, while control animals kept in the laboratory a comparable length of time showed little fluctuation in quantity of excreted urine. Neither the duration nor conditions of short-term captivity influenced urine mineral levels of normal iguanid lizards.