This paper presents a clinical specular microscope for the examination and photography of endothelial cells at high magnification (X200). The instrument is used easily during routine examination without inconvenience or discomfort to the patient. We have found the specular microscope extremely useful clinically in the elucidation and documentation of corneal endothelial diseases in vivo. This instrument allows the detection of endothelial damage or disease which may not be seen by slitlamp examination. The effects of normal aging, endothelial dystrophies, trauma, and inflammation can be monitored. The instrument is especially useful in the evaluation of ocular surgical procedures. It can be used on the first postoperative day without inconvenience to the patient or damage to the eye. By the comparison of photographs taken before and after the operation, an estimate of endothelial cell loss may be made. Thus, the endothelial effects of different techniques of cataract extraction intraocular lens insertion, and penetrating keratoplasty can be observed and compared. This new technique for the clinical examination of corneal diseases has great promise in improving diagnosis as well as therapy.