Abstract: Among the various methods for the evaluation of analgesics,the“hot-plate” method has advantage of its simplicity and fair reliability. The original method,as introduced by G.Woolfe and A.D.Macdonald,has been modified,so that the response time is recorded instead of recording only the existence of responses within the fixed duration of time.By this modification it has been found that this method can serve as a semiquantitative method for com- paring the pain-threshold raising activity of various analgesics. The mice used should be of uniform stock with regard to weight,sex and age,and those having exceedingly high or low response to stimulation shoud be discarded.Being greatly influenced by room temperature,tests carried out under different room temperatures would yield results of little quantitative meaning;results obtained under identical experimental conditions can,however,indicate in a semi- quantitative sense the potency of a new analgesic under test.