Forty-eight eyes with massive periretinal proliferation were examined with ultrasonography. In addition to the triangular retinal detachment T-sign was indicative of severe MPP. And irregular thickening and bending of the retina were observed on ultrasonography in eyes with MPP. The detached retina was immobile in all eyes. Preoperative ultrasonographic findings did not prove the value on the assessment of operative prognosis. REFERENCES Bronson, N.R. & Turner, F.T. A simple B-scan uitrasonoscope. Arch. Ophthalmol. 90: 237 (1973). Coleman, D.J., Koning, W.F. & Katz L.: A Hand-Operated ultrasound scan system for ophthalmic evaluation, Am. J. Ophthalmol. 68: 258 (1969). Fuller. D.G., Laqua, H. & Machemer, R. Ultrasonographic diagnosis of massive periretinal proliferation in eyes with opaque media (triangular retinal detachment). Am. J. Ophthalmol. 83: 460 (1977). Laqua, H. & Machemer, R. Glial cell proliferation in retinal detachment (massive periretinal proliferation). Am. 1. Ophthalmol. 80: 1 (1975). Laqua, H. & Machemer R. Oinical-pathological correlation in Massive periretinal proliferation. Am. J. Ophthalmol. 80: 912 (1975). Machemer, R. & Laqua, H. Pigment epithelial proliferation in retinal detachment (massive periretinal proliferation). Am. J. Ophthalmol. 80: 1 (1975). Machemer, R. & Laqua, H. A logical approach to the treatment of massive periretinal proliferation. Ophthalmology 85: 584 (1978). Machemer, R. Van Horn, D. & Aaberg, T.M. Pigment epithelial proliferation in human retinal detachment with massive periretinal proliferation, Machemer, R. Pathogenesis and classification of massive periretinal proliferation. Br. J. Ophthalmol. 62: 737 (1978).