Diabetic retinopathy represents a serious health threat to a rapidly growing number of patients with diabetes mellitus. The retinal microangiopathy is characterised by vascular lesions with exudate deposits and haemorrhages causing vision loss. Pycnogenol, a standardised extract of the bark of the French maritime pine (Pinus pinaster), is known to increase capillary resistance. Pycnogenol has been tested for treatment and prevention of retinopathy in five clinical trials with a total number of 1289 patients since the late 1960's. All but one of these studies have been reported in French and German and, today, are of limited accessibility, giving the impetus for reviewing them in detail in this article. There were two open case studies and two double blind studies (one controlled against calcium dobesilate and another against placebo) and, finally, one multi-center field study with 1169 diabetics. All of these studies unequivocally showed that Pycnogenol retains progression of retinopathy and partly recovers visual acuity. Treatment efficacy of Pycnogenol was at least as good as that of calcium dobesilate. Pycnogenol was shown to improve capillary resistance and reduce leakages into the retina. Tolerance was generally very good and side effects were rare, mostly referring to gastric discomfort. In conclusion, treatment with Pycnogenol had a favourable outcome in the majority of the patients with diabetic retinopathy.