Iridology is an analysis of health based on examination of the iris of the eye. One hundred forty-three patients had photographs taken of both eyes. Nine-five patients were free of kidney disease, defined as a creatinine level of less than 1.2 mg/dL (mean, 0.8 mg/dL), and 48 had kidney disease severe enough to raise the plasma creatinine level to 1.5 mg/dL or greater (mean, 6.5 mg/dL). Three ophthalmologists and three iridologists viewed the slides in a randomized sequence without knowledge of the number of patients in the two categories or any information about patient history. Iridology had no clinical or statistically significant ability to detect the presence of kidney disease. Iridology was neither selective nor specific, and the likelihood of correct detection was statistically no better than chance.