Kinetic perimetry was carried out using the Goldmann perimeter in 201 patients with primary pigmentary retinal dystrophy, 156 autosomal recessive and 45 autosomal dominant cases. "The advanced stage" of the isopter deterioration was defined as the isopter area with the test object I-4 being 1 cm2 or less on the chart of Goldmann. The frequency of "the advanced stage" cases in creased with age in both hereditary forms, but it was higher in the recessive than in the dominant form throughout all age groups. The frequency-age relationship was exponential as is found in various aging phenomena. Fifty per cent of the patients were in "the advanced stage" at the age of 30 years in the recessive and at the age of 56 years in the dominent form.