Summary—The treatment of idiopathic hypercalciuric stone formers with the prostaglandin synthetase inhibitors flurbiprofen and indomethacin has been studied in two phases. Ten patients were studied in a metabolic unit for 14 days that included a control period of 7 days on a controlled intake of dietary calcium, followed by treatment with flurbiprofen 50 mg tds. Three patients were studied along similar lines and were treated with indomethacin 25 mg tds.A significant reduction in urinary calcium excretion was noted during the 7‐day control period during which dietary calcium intake was reduced to 700 mg daily. No further significant reduction in urinary calcium excretion was observed during the treatment with either flurbiprofen or indomethacin.Thirteen patients then continued to take flurbiprofen 50 mg tds for between 1 and 12 months. A small but not statistically significant reduction in urinary calcium excretion was noted by the third month of treatment, but this was not sustained.This study confirms the benefit of dietary restriction of calcium as the primary approach to the treatment of idiopathic hypercalciuria. Neither flurbiprofen nor indomethacin reduced urinary calcium excretion to significant levels. Their routine use for the treatment of idiopathic hypercalciuria cannot be recommended from the evidence of this st