Acute corneal endothelial changes following Nd:YAG laser application were evaluated in two series of rabbits. The first series underwent anterior capsulotomy, while the second series received laser applications at calculated distances ranging from 0.0 mm to 1.8 mm posterior to the endothelium. The rabbits were killed 24 hours after treatment and the endothelium evaluated with scanning electron microscopy. None of the eyes undergoing anterior capsulotomy showed endothelial damage, but the endothelium was focally denuded when laser shots were applied within 1.0 mm of it, and Descemet's membrane was disrupted by laser shots focused within 0.1 mm. Implications for clinical laser surgery are discussed.