The purpose of this study was to clarify the effect of intracana1 medication on the clinical symptoms and the number of visits before canal filling in endodontic treatment The experimental teeth was divided into three groups. The teeth of group 1 was irrigated with saline solution and the teeth of group 2 was irrigated with sodium hypochlorite during biomechanical preparation. The intracanal medicament was not applied in the canals of group 1 and group 2. The teeth of group 3 was irrigated with sodium hypochlorite and hydrogen peroxide during canal enlargement and applied formocresol as intracanal medicament after drying the root canals with paper points. The incidence of interappintment pain and percussion pain after 1 st visit and the number of appointments before canal filling was examined, and the results was statistically compared. The following results were obtained. 1. The incidence of interappointment pain and percussion pain and the number of visits before canal filling was not effected by the types of irrigant and the use of the intracanal medicament 2. There was no significant difference in the incidence of interappintment pain arid percussion pain and the number of appointement before canal filling between vital teeth and non vital teeth, and also between single rooted teeth and multirooted teeth. 3. The use of formocresol as intracanal medicament was not able to aid the elimination of clinical symptoms and to decrease the number of appointment before canal filling.