In 34 individuals with a spectrum of clinical manifestations of Bancroftian filariasis, we investigated whether immunoperoxidase-stained, random, superficial dermal biopsies could further elucidate the nature of the diffuse damage to superficial lymphatics that had been recently demonstrated by radionuclide lymphoscintigraphy. A total of 78% and 68% of limbs from patients with clinical disease and asymptomatic microfilaremia, respectively, contained EN4+PAL-E- lymphatic vessels that were abnormally dilated. The majority of subjects, regardless of clinical classification, had a CD3+ perivascular but not a perilymphatic infiltrate in tissues and no parasites were present. In contrast to those individuals with asymptomatic infection, a striking predominance of CD8+ T cells was found in the tissue of individuals with clinical disease. Tissue pathology consistent with cutaneous bacterial infection was not observed. The prominent perivenular and pericapillary mononuclear infiltrates likely indicate, in light of current understanding of lymphocyte recirculation, the extravasation of lymphocytes from the vascular circulation into the inflamed filarial tissue.