Despite the increasing ACT teams in Japan, no research exists on the need of ACT within the Japanese mental health system. The aim of this study was to describe the needs and feasibility of ACT teams. Furthermore, we estimated the number of po-tential ACT users and ACT teams needed in Japan. This study consists of two cross-sectional surveys in Sendai city. The primary survey was a self-completed questionnaire on the need and feasibility of ACT. In the secondary survey, the number of patients eligible for ACT was estimated based on primary physicians' evaluations. In the primary survey, 17 of the 57 in-stitutions responded (response rate 29.8%). All respondents answered that ACT teams are needed in the city of Sendai and "Crisis response" was as the most needed role of ACT. Based on the results of the secondary survey, approximately 900 to 3,600 patients in Sendai are estimated to be eligible for ACT. This finding indicates that the estimated number of ACT teams needed for 100,000 populations is from 0.9 to 3.5 in Japan, a result that is in general agreement with data from other coun-tries.