Precast prestressed hollow-core concrete flooring units are widely used in reinforced concrete moment-resisting frame buildings in New Zealand, yet their behaviour under fire has not received much attention. This is because large scale fire tests are difficult and expensive, leaving computer analysis as the only alternative. However, the currently available computer analysis methods are neither accurate nor easy to use. This paper describes a simple yet reliable computational method to be used in design for modelling the structural behaviour of hollow-core prestressed concrete slabs exposed to fires. The model has a major limitation of not being able to model shear or tensile failure in the webs of the hollow-core units, but the simulation outcomes show reasonably good agreement with experimental fire tests of hollow-core slab units, thereby verifying the reliability of the model.