The authors studied 80 eyes of patients with choroidal neovascular membranes (CNVMs) associated with age-related macular degeneration between 1982 and 1988. In each case, fluorescein angiography was done on two occasions separated by an interval of 2 days to 11 weeks (average, 13 days) without intervening photocoagulation. Forty-three CNVMs (54%) grew toward the fovea during the interval between fluorescein angiograms, with growth rates ranging from 1 to 24 microns daily (average, 10 microns daily). The CNVM growth was related to the time interval between angiograms (P less than 0.0001), but was not associated with morphologic features of the CNVM. These results reinforce the need for early detection and prompt evaluation of elderly patients with symptoms of CNVMs.