Tamm Horsfall glycoprotein (THG) is a major constituent of renal tubular casts including the light chain casts of myeloma. Animal studies suggest that the anti-inflammatory agent colchicine reduces urinary THG excretion and prevents light chain cast formation. Six normal male subjects were given therapeutic doses of colchicine (0.5 mg twice daily for 6 days) and excretion of THG, albumin, creatinine and N-acetyl glucosaminidase (NAG) was determined. Colchicine therapy had no effect on the urinary excretion of THG, albumin or NAG or on renal function as assessed by creatinine clearance. This suggests that colchicine will not be a useful therapeutic adjunct to the treatment of light-chain nephropathy.