Proliferative, papillary vulvitis was identified in 16 of 34 (47%) free-ranging and captive female Florida panthers (Puma concolor coryi) monitored over a period from 1983–98. Gross lesions were characterized by extensive papilliferous proliferation in the mucosa of the vestibulum vaginae. Within lesions, the mean length and width of vestibular papillae were 1.07 ± 0.39 mm (CV = 36%) and 0.55 ± 0.11 mm (CV = 20%) respectively. Histologically, three to 12 layers of non-cornified stratified squamous epithelium with various degrees of basal cell spongiosis and rete ridge formation covered fibrous papillae. Mixed leukocytic mucosal inflammation also was observed. Infectious organisms were not observed, and immunohistochemical testing for the presence of papillomavirus antigens in specimens from seven panthers was negative. Lesions in nearly all of the panthers were first observed during a six-year period (1986–92), with one each in 1983, 1996 and 1998. There were no significant differences between the number of females having litters, the number of litters between age-matched and interval-matched females, and the interval between litters among lesion positive and lesion negative females over the 15 yr period. The severity of lesions did not appear to differ between parous and nulliparous free-ranging lesion-positive females. The cause of proliferative vulvitis remains unknown. However, the lesion did not appear to have a significant effect on reproduction.