A software release is a collection of new and/or changed features that form a new product. Release planning is a very complex problem including different stakeholder perspectives, competing objectives and different types of constraints. Most of the information is usually uncertain. Under such circumstances, the use of crisp values is only an approximation of reality.

In this paper, we propose an approach improving existing methods for release planning by handling the uncertainty of data using fuzzy logic. Concretely, we consider fuzziness with respect to the effort estimates, effort capacity constraints and the different objectives related to cost, benefit and quality. The satisfaction of traditional constraints on effort is performed using a fuzzy system to obtain an overall satisfaction level of a solution. This is considered to be an essential support for the actual decision-making. All the proposed concepts and the complete approach are illustrated by a case study example.