The anti-DNA antibody titer (heat denatured, native and monostranded) was studied in 61 patients with psoriasis and 41 healthy controls. Positive titers of anti-DNA antibodies were established in 19.3% of the psoriatics and in 4.9% of the controls. Antibodies against heat-denatured DNA were discovered in 8.2% of the patients and in 0% of the healthy persons; against native DNA in 18% of the psoriatics and 4.9% of the controls and against monostranded DNA in 31.7% of the psoriasis patients and 9.8% of the control group. In general, the percentage of the positive titers of anti-DNA antibodies in psoriatics was about 4 times higher than that of the healthy controls.