Open-space preservation is a planner's issue that is constantly debated, in particular on the success of the implemented instruments. Assessments of policy effectiveness face many methodological problems that are briefly discussed here. We choose to analyse the contribution of Dutch policies to open-space preservation by comparing actual land-use developments within different restrictive planning regimes. The presented analysis differs from comparable efforts that usually rely on census statistics through its use of local-level geographical data and spatial analysis techniques. Our approach has the advantage of being able to analyse the impact of spatially explicit regional zoning regulations. In addition to comparing regions with strict and less strict regimes, this paper also assesses the importance of another open-space characterisation. The latter refers to a distinction in agriculturally shaped and exploited landscapes and natural areas. We conclude the analysis with a discussion on possible spatial planning implications. © 2007 Elsevier Ltd. All rights reserved.