The use of an information system as a competitive weapon is, of course, a topic of considerable interest these days. Usually the interest is centered on the for-profit sector, where notions of combat in the marketplace are not at all foreign. Competition among organizations in the not-for-profit sector, such as hospitals and universities, is usually thought to be more muted and genteel. As organizations in the non-profit sector fight for survival in an increasingly harsh environment, however, there is no reason for them to forego potential strategic advantages through the use of information technology.Based on a series of four case studies, this article examines the conditions under which a hospital might expect to gain competitive advantages. The special culture of a hospital, in which physiCians hold a great deal of power relative to the hospital administration, must certainly be taken into account. The authors also assert that strategic systems must generally integrate the more traditional transaction processing and information reporting systems. When done right, though, a health care organization can expect to achieve competitive advantages through its information system. The article has obvious relevance for those involved in health care institutions. It also has broader implications, however, because the issues discussed-e.g., the importance of taking account of organizational culture and the need for a strategic system to penetrate into operational activities-have general applicability. MIS Quarterly/June 1990