In every case of an uncertain vertical diplopia one should think of an endocrine ophthalmopathy. A squint operation done in time will improve the motility of the eye. 8 of our 9 patients had no longer a diplopia after surgery and got binocular vision. 6 months after stabilization of the endocrine situation we resected and recessed the rectus muscles, especially the vertical rectus muscles, in 1 case we advanced the inferior oblique muscle. The amount of the surgical correction depended on the motility disturbance and the angle of squint which we compensated a few days before the operation by means of prisms. Postoperatively the patients got steroids parenterally.