In diabetes mellitus, both retinopathy and nephropathy represent specific microvascular disease with increased capillary permeability resulting in hard exudates, foveal oedema, and albuminuria. The decrease of heparan-sulphate content of the glomerular-basement membrane is quantitatively related to the rate of proteinuria in nephropathy associated with insulin-dependent diabetes mellitus (IDDM). Several short-term studies in patients with IDDM and non-IDDM have shown that a reduction of microalbuminuria and macroalbuminuria can be achieved with the supplementation of glycosaminoglycans. After completion of a study on the effect of danaparoid sodium on albumin excretion in patients with IDDM and macroalbuminuria, we hypothesised that treatment with danaparoid sodium also influenced retinal leakage in the patients in that trial. In this retrospective study nine patients with nephropathy received 750 anti-Xa units danaparoid sodium once a day for 6 weeks in a placebo-controlled double-blind cross-over study. Fundus photographs, done at baseline and at the end of the study, were semiquantitatively scored for the severity of hard exudates. At baseline 14 eyes had grade 1 to 5 severity of hard exudates and four eyes were without hard exudates (grade 0). There was no progression in the latter four eyes. In ten eyes an improvement was observed: four patients showed a favourable response to treatment in both eyes and two patients showed improvement in one eye. We found improvement of hard exudates after 6 weeks of treatment with danaparoid sodium. Our uncontrolled observation indicates that the supplementation of danaparoid sodium influences both the permeability of retinal vessels as well as of glomerular vessels. Danaparoid-sodium therapy as a systemic adjuvant is worth considering for treatment strategies for foveal oedema and hard exudates in diabetic maculopathy.