Studies suggest the independent appearance of anti-DNA in the sera of patients with selected microbial diseases (whether or not ocular involvement is manifested), and the other antibody demonstrations accepted as evidence of the disease in question. Serum anti-DNA is more frequently encountered in patients with diseases of microbial than of nonmicrobial origin, or than in normal subjects. By the techniques employed, the demonstration of serum anti-DNA was not persistent in the serially procured sera of patients included in the study. © 1968.