In Type II lepromatous reaction, there is exacerbation of humoral immunity, classified as Gell & Coombs Type III hypersensitivity reaction. It is more common in lepromatous borderline (LB) and lepromatous lepromatous (LL) patients. Our objective was to study the clinical and laboratorial expressions of lepromatous Type II reactions, establishing concordances between them, and for this the medical records of leprosy patients observed at the Clementino Fraga Filho University Hospital of the Federal University of Rio de Janeiro (HUCFF/UFRJ) were reviewed. There were a total of 358 leprosy cases over a period of 12 years. Demographic, clinical, and laboratory data of 133 patients with Type II reaction were collected. Among the 133 patients, 19 were classified as borderline borderline (BB), 15 (11.3%) as LB, and 97 (72.9%) as LL. Mitsuda intradermal reaction was negative in all the 49 patients who underwent this test. Histopathologic study confirmed the diagnosis. Lepromatous patients (LP) presented positive bacilloscopy more frequently (73.91% of 68 patients) than borderline patients (BP) (26.9% of 24 patients). Among BP, 44% presented erythema nodosum leprosum (ENL), which was seen in 71% of LP. Erythema multiforme (EM) occurred in 32% of BP and 13% of LP. Lucio phenomenon (LPh) was observed in 8 of 34 BP (23.6%), and 15 of 97 LP (15.4%). The understanding of the laboratorial and clinical presentations of reactional episodes are relevant to the development of preventive and therapeutic strategies, in order to avoid potential complications and comorbidities that cause disability, paralysis, deformities, and stigma of leprosy.