AIM: To explore the influence of a cilio-retinal artery on diabetic maculopathy. METHODS: In the county of North Jutland 481 diabetic subjects underwent examination for diabetic retinopathy during the period 1 June 2000 to 30 June 2001. A unilateral cilio-retinal artery was observed in 104 patients among which 29 revealed variation in right and left eye maculopathy. A bilateral cilio-retinal artery was observed in 15 diabetic subjects. The influence of a cilio-retinal artery on diabetic maculopathy was explored in a paired study. RESULTS: Diabetic maculopathy was found to be more severe in 26 of 29 eyes with a cilio-retinal artery (p<0.01) compared to eyes without it. The number of red dots (p<0.0001) and hard exudates (p=0.0002) were found to be significantly increased in eyes with a cilio-retinal artery, as also the number of eyes with central photocoagulation (p<0.05). In addition, clinically significant macular oedema was found to be significantly increased in eyes with a cilio-retinal artery compared to eyes without it (0.01<p<0.02). CONCLUSION: In some patients, the presence of a cilio-retinal artery may worsen diabetic maculopathy.