Gonioscopy is the technic of examination of the angle of the anterior chamber of the eye. This structure, ordinarily concealed from view by the opaque edge of the scleral limbus, is made visible by contact lens and oblique illumination. Although gonioscopy is a comparatively young science, dating from 1913, it has grown to be an important part of ophthalmology. Dr. Troncoso has written a clearly expressed, beautifully printed and illustrated text on this subject, of which he is an authority and pioneer. Ophthalmologists will welcome it.