Eighty-three choroidal neovascular membranes (CNVMs) associated with pathologic entities other than age-related macular degeneration (study group) were compared with 64 CNVMs associated with macular degeneration (comparison group). Nine CNVMs (11%) in the study group, compared with 28 CNVMs (44%) in the comparison group, were occult membranes. Of the remaining well-defined CNVMs, 16 (22%) in the study group, compared with 21 (58%) in the comparison group, were subfoveal. Of the well-defined subfoveal membranes, four (25%) in the study group, compared with 17 (81%) in the control group, were large (greater than 1500 micron in size). All large subfoveal membranes occurred in patients over 55 years of age. Thus, in this study the majority of CNVMs associated with pathologic entities other than age-related macular degeneration were well defined and not subfoveal at initial presentation. The majority of CNVMs associated with macular degeneration were occult or subfoveal. Membranes in patients over 55 years of age, regardless of cause, were commonly found to be occult or subfoveal at presentation.