Abstract: Dirofilaria tenuis is a mosquito-transmitted filaria of raccoons in the American Southeast. Here, we report the case of subcutaneous D tenuis in a 72-year-old south Florida resident. A 1-cm nodule on the left forearm progressed to an extensive inflammation and radial neuritis with stiffness and weakness of the thumb, index, and middle fingers. His serum was positive for antifilarial IgG1. The determination was based on the history of exposure in Florida and on the characteristics of the degenerating body wall. Removal led promptly to resolution. Subcutaneous D tenuis is usually benign and may simulate lipomas or neoplasms almost anywhere on the body. It should be considered in middle-aged or older patients of either sex who present with a small nodule enveloping a slender coiled roundworm (females, 260–360 μm × 8–13 cm). Florida has accounted for approximately 3 quarters of reported cases.