Summary Sand-glass and tetraedric crystals often occur in cytologic evaluations of urinary sediments as a secondary finding. The analyses show inflammation and an increase in protein casts as accompanying changes. The basic diseases are primarily renal but unspecific. The analyses of the crystals by laser-ray-technique (LAMMA®-analysis)demonstrate calcium in the positive ionic spectrum in both forms. Differences can be registered in the negative ionic spectrum: sand-glasses and small tetraeders contain considerable amounts of phosphate (PO 2 − and PO 3 −), while only the larger tetraedric crystals consist of pure calcium oxalate.