Purpose: The purpose of this research is, by investigating organizational characteristics, types of nursing organizational culture and team effectiveness in ICU, to ascertain the type of nursing organizational culture and the organizational characteristic that can improve the team effectiveness. Method: The research targeted 427 nurses from 33 ICUs of 14 general hospitals which have more than 250 beds and the data were gathered by using self-report questionnaires from April 10, 2003 to April 24, 2003. For this research, the following tools were used; the tool for measuring organizational characteristics and organizational cultures and the tool for measuring team effectiveness. Result: The most significant nursing organizational characteristic in ICU is the centralization. The organizational culture in ICU is generally rank-oriented culture. There was a significant difference (p<.01) in four types of organizational cultures; relation-oriented, innovation-oriented, rank-oriented and task-oriented. Verifying influence power of organizational cultures upon team effectiveness of ICU, relation-oriented culture had 49.2% of an influence upon team effectiveness, innovation- oriented and relation-oriented culture had 60.4% of an influence, and rank-oriented, innovation-oriented and relation-oriented culture had 61.2% of an influence. The organizational culture profiles according to the types of nursing organizational cultures in 33 ICUs were found by a cluster analysis. They were classified into five culture profiles; strong balance culture profile, weak balance culture profile, innovation-oriented and task-oriened culture profile, strong relation culture profile and strong rank culture profile(p<0.5). According to me organizational culture profiles, a significant difference of team effectivenesses(coworker satisfaction, team performance perception, team satisfaction and team commitment) was found(p<.01). The strong balance culture profile had the best team effectivenesses. Conclusion: For nursing culture management, a nursing administrator should identify the relevant nursing organizational culture at first by utilizing an innovative team-leader. After identifying the organizational culture, the administrator should make strategic plans and practices that can distinguish good organizational cultures to be expanded from ones to be sublated so that a strong balance culture can be developed.