1. The progress of the retinopathy after pituitary implantation has been followed for 1--7 years (mean 2 years) in 60 diabetic patients and assessed from gradings of the retinal photographs and visual acuity measurements. --2. The degree of hypopituitarism induced (by three different yttrium 9~ dosages) had varied and has been assessed by tests of thyroid and adrenal function into three grades of ablation, "maximal", "intermediate" and "slight". --3. In the whole group, while exudates, retinitis proliferans and visual acuity did not improve, haemorrhages and microaneurysms, new vessels and venous irregularities had improved after 1 year, and these continued improving up to the latest assessment. --4. On comparing the outcome at either 1 year or the final assessment, the effects of "maximal" or "intermediate" pituitary ablation appeared equivalent, but clearly superior to "slight" ablation. In particular, haemorrhages and microaneurysms showed equal improvement postimplant in all three ablation categories. New vessels improved in the "maximal" and "intermediate" ablation categories equally, but not in the "slight" category. Venous irregularities improved discernibly only after "maximal" ablation, l~etinitis proliferans deteriorated in all three ablation categories, although "maximal" was more effective than "slight" in preventing new lesions. Visual acuity declined only in the "slight" category.La rdtinopathie diabgtique. II. Comparaison des dtats de rgmission de la maladie, provoquds par diffgrents degrds de destruction de l'hypophyse par de l'yttrium 9~ Rdsumd. 1. L'dvolution de la rdtinopathie apr~s ,,maximalen" und ,,mittleren" Sch~digungsgruppe gleich, jedoch nicht in der ,,leiehten" Gruppe. Die Venenunregel-mi~i~igkeiten besserten sich erkennbar nut nach ,,maximaler" Sch~digung der Hypophyse. Die l~etinitis proliferans verschleehterte sich in allen drei Gruppen, obwohl die ,,maximale" Gruppe weniger neue Sch~den erkennen liel3 als die ,,leichte". Die Sehsch~rfe nahm nut in der ,,leiehten" Gruppe welter ab.