Acute calcium deposits are characterized by acute pain and a radiographic finding of amorphous calcification. A prospective, observational study was carried out on 30 consecutive patients undergoing conservative treatment for acute calcium deposits of the hand and wrist. Thirteen patients presented with acute calcific peritendinitis (Group A), and the other 17 with acute calcific periarthritis (Group B). All patients were followed for more than 12 months (mean 29 months). The average age at onset and recurrence rate of acute calcific peritendinitis were both significantly greater than for acute calcific periarthritis.