The collagen-dissolving ability of both 2.6% and 5.2% sodium hypochlorite endodontic irrigating solutions was compared at room temperature (21 degrees C) and body temperature (37 degrees C). The 2.6% sodium hypochlorite solution at a temperature of 37 degrees C. was found to be equally effective as a collagen-dissolving agent when compared to 5.2% sodium hypochlorite at either 21 degrees C. or 37 degrees C.