Chiracanthium japonicum, the most common spider making house with leaf of Graminaceae, is well known as venomous for a person. During the period from 1956 to 1974, five bite cases of this species were reported from various districts in Japan. These cases were classified by the severity of clinical manifestation into four types, symptomless, mild, moderate and severe. Four bite cases in all cases were occurred by male and two bite cases were of the severe type. The most serious problem in the trearment was difficulty in relieving continuous sharp pain by any anodynes or sedatives.
