Zn accumulation (gettering) in InGaAs/InP interfaces was studied experimentally using secondary ion mass spectrometry (SIMS). The Zn was introduced by diffusion from solid and gaseous sources and was found to often getter in a thin region at the interface when diffused across it. Its peak concentration there increased with diffusion time and temperature and in some cases exceeded the solid solubility value by two orders of magnitude. Possible mechanisms for the Zn gettering are discussed.