Since reports of factitious disease have increased, we reviewed the analyses of 5,565 specimens submitted as urinary tract calculi (1979–1987) for artifacts, that is, those stones not formed of accepted constituents of urinary calculi. These include artifacts from 3,300 stones previously reported (1). Artifacts numbering 168 (3.1%) were submitted by 102 patients including 68 females. Analytical methods included infrared- and wet-chemical analyses, x-ray, x-ray diffraction spectrometry (when geological origin was suggested), histochemistry, and microscopy (when indicated), and, occasionally, polarizing petrographic microscopy and mass spectrometry. Forty-six artifacts from 29 patients were of organic origin and many were undoubtedly submitted by accident as calculi, especially by women. Sixty-one patients submitted 109 specimens which were of geological origin. These were mainly silicates as quartz and/or feldspar which commonly occur together in granite. Twelve patients submitted 13 metallic artifacts. The great majority of inorganic artifacts were submitted for secondary gain (for example, to procure drugs), or for psychiatric reasons. Eighteen patients submitted 2 to 15 artifacts. One or more artifacts were submitted by 23 patients who also submitted one or more true urinary calculi. In 16 patients, the first specimen analyzed was a true stone. Substance abuse may follow the pain and treatment of multiple calculi, and management decisions for such patients can be very difficult. Confounding specimens included: a) those with silicate which may form true calculi in patients ingesting medication containing silicates; b) calcium carbonate which we suggest is most often an artifact, for example, a seashell; and also c) specimens of plant origin which contained oxalate.