In addition to monosodium urate, calcium pyrophosphate dihydrate, and apatite crystals, oxalate crystals are less often found in synovial fluids in association with acute or chronic arthritis. Oxalate crystal deposition disease is seen in patients with primary hyperoxaluria types 1 and 2 (PH1 and 2) and in patients with end-stage renal disease managed with long-term dialysis. Oxalate crystal deposits are found mainly in kidneys, bone, skin, and vessels, and less often inside the joints. Musculoskeletal and systemic manifestations of oxalate crystal deposition disease may be confused with those observed with the other most common types of crystal deposition diseases. Clinical and radiographic features include calcium oxalate osteopathy, acute and chronic arthropathy with chondrocalcinosis, synovial calcification, and miliary skin calcium oxalate deposits and vascular calcifications that affect mainly the hands and feet. Systemic life-threatening cardiovascular, neurologic, and hematologic manifestations are rare. Genomic DNA studies have identified those genetic defects of PH1 and PH2 that allow a precise early diagnosis. Kidney transplantation has poor outcome as a result of graft oxalosis. Combined liver and kidney transplantation is the treatment of choice in patients with PH1 and advanced renal failure. Pre-emptive isolated liver transplantation is the preferred treatment in patients who develop the disease during infancy with progressive manifestations of oxalosis. These novel findings in the understanding of the molecular and enzymatic aspects of primary hyperoxalurias have provided a more rational basis for the management and prevention of oxalate crystal deposition disease. This information may lead to a better understanding and effective management of other common calcium-containing crystal deposition diseases.