Several skin diseases associated with immune disorders may be related to the formation of circulating immune complexes (CIC) and their skin deposition. Sera from 20 controls and 108 patients, including: 23 psoriasis, 10 lichen planus, 30 atopic eczemas, 32 cases of leprosy, 10 vasculitis and 3 pyoderma gangrenosum were evaluated for the presence of IgG-containing CIC by the microconsumption complement test (MCT). Additionally, the presence of IgE-containing CIC by means of a polyethylene glycol precipitation and radioimmunoassay technique was evaluated in 10 patients with atopic eczema. It was found that 56.5% of psoriatic patients show moderate CIC concentrations, as well as 34% of leprosy patients, with increased levels when bacillus were detected in skin lesions, and in 90% of leukocytoclastic vasculitis. A close relationship between CIC levels and the clinical evolution of skin lesions was demonstrated in patients with pyoderma gangrenosum and lichen planus. IgG-CIC were detected in 33% and IgE-CIC in 30% of patients with atopic eczema, with the presence of both types of CIC in 2 out of 3 cases. The systematic research on CIC presence in some selected skin diseases shows that immune complexes take part, with different degrees of relevance, in the pathogenesis of all the entities.