Fifty total hip arthroplasty (THA) patients and 24 total knee arthroplasty (TKA) patients were randomized in a controlled study to examine the effects of cold therapy (via thermal blankets) in the postoperative period. The postoperative hospital stay was significantly shorter for the cold-therapy (50 degrees F) compared with control (70 degrees F) groups (by 1.4 days, P = 0.03) for THA patients. There was a similar but nonsignificant trend observed in the TKA groups (1.5 days shorter, P = 0.19). Total knee arthroplasty patients using cold therapy achieved independent ambulation an average of 1 day sooner than TKA control patients, but this difference did not reach statistical significance (P = 0.08). There were no statistically significant differences between the control groups or the test groups for both THA and TKA patients in narcotic usage, postoperative range-of-motion (ROM), or rate of progression of ROM.