The present study investigates the blood pressure (BP) 24 h pattern in 25 subjects who were found to show some incipient signs of hypertensive retinopathy, although they were diagnosed as normotensive by means of casual sphygmomanometry. BP was controlled by means of non invasive ambulatory monitoring. A comparable number of normotensive subjects without fundoscopic signs of hypertensive retinopathy was investigated as a control group. BP times series were analyzed by means of conventional and rhythmometric biometry. The biometric estimates suggest that the subjects with incipient hypertensive retinopathy show a significantly higher level of daily systolic BP even though their BP values remain below the reference limits. This finding suggests that the hypertensive retinopathy may exist in a non-zero stage characterizable as minimal change tensive retinopathy. This retinal picture occurs in subjects who show a pre-hypertensive stage in their BP 24 h pattern.