The effects of interface recombination on measured minority-carrier lifetime in n-type liquid-phase epitaxial GaP layers have been studied quantitatively. Results are presented for a number of different interface conditions, and analysis shows that the interface recombination velocity is high in all cases. This results in a unique dependence of interface-recombination-controlled lifetime τs, on layer thickness t for all values of t > ∼0.5 μm. In most layers, the value of τs is low enough to influence the measured lifetime. A value for the minority hole diffusion coefficient, Dh = 4.0±0.3 cm2 s−1, is also deduced from the τs data.