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Single dislocations in epitaxial layers of GaP have been investigated using high resolution scanning electron microscope (SEM) cathodoluminescence (CL) techniques. The minority carrier lifetime was measured from the CL decay time constant, and impurity concentrations were assessed from a detailed analysis of the CL spectra. The minority carrier lifetime reduction at single dislocations varied between 10 and 40% depending on doping and growth procedure, decreasing to zero at approximately one diffusion length from the dislocation. A model based on recombination at an internal cylindrical surface did not adequately fit the experimental results, and it was therefore assumed that recombination occurred at a Cottrell atmosphere of impurities or defects surrounding the dislocation. Evidence to support such behaviour was obtained from CL spectra, which showed aggregation of nitrogen and a centre, probably a vacancy-donor complex, at 1.72 eV around dislocations. The close similarity between bulk and dislocation temperature dependence of lifetime suggests that the bulk recombination centre may be aggregating around dislocations.