Since the second half of the eighties production of greenhouse tomatoes in Belgium was characterized by a growing importance. Tomatoes became the most important vegetables produced in Belgium. However in the last few years competition with the developing horticultural production in the southern regions (especially Spain) became very hard and resulted in a serious economic crisis in the year 1995. In the paper different strategies Belgian growers can adapt in order to improve their competitive position are evaluated. The theories of Porter (1980, 1985, 1990) describe three basic strategies for acquiring competitive advantage: a cost advantage strategy, a differentiation strategy and a focus strategy: In the Farm Accountancy Data Network of the Centre of Agricultural Economics economical as well as technical data are collected at holdings with glasshouse vegetables. An analysis of these data shows that the success of Belgian greenhouse tomato production during last decade was determined by an important increase in production per m(2), resulting in decreasing costs per kilogramme of tomatoes. However in the future the effect of further increases in productivity will become less important. As a consequence particular emphasis must be placed on quality and differentiation strategies. This implies the setting up of integral quality management systems.