Hypertension is an established risk factor for retinopathy. Whether it is an independent risk factor or acts only by association with nephropathy is not known. Therefore, we studied 273 Type 1 diabetic patients. They were divided into four groups. Group 1 (n = 55) were normotensive and normoalbuminuric, group 2 (n = 51) had hypertension but were normoalbuminuric, group 3 (n = 33) had nephropathy but were normotensive, and group 4 (n = 134) had nephropathy and hypertension. Hypertensive patients with normoalbuminuria (blood pressure 146 +/- 19 (+/-SD)/87 +/- 12 mmHg) had the same prevalence of retinopathy as normoalbuminuric normotensive patients (123 +/- 12/75 +/- 5 mmHg). Hypertensive nephropathic patients (blood pressure 147 +/- 18/87 +/- 8 mmHg) had more retinopathy than hypertensive normoalbuminuric patients despite similar blood pressure (normal retina/advanced retinopathy: 3%/73% vs 46%/17%, p less than 0.001). Nephropathic normotensive patients had worse retinal changes than hypertensive normoalbuminuric patients (19%/49%, p less than 0.001) but fewer than the nephropathic hypertensive patients p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)