A subset of patients with pediatric onset obsessive-compulsive disorder (OCD) and tic syndromes (e.g. Tourette's syndrome) have symptom onset or exacerbation associated with infection. Some of these patients have been demonstrated to have antineuronal antibodies reactive with nuclei of the basal ganglion. It has been hypothesized that these patients have an immune process initiated by infection that affects the basal ganglion and causes obsessive-compulsive symptoms. The term pediatric autoimmune neuropsychiatric disorders associated with strepococcal infections (PANDAS) has been coined to describe those patients with evidence of recent group A beta hemolytic streptococcal infection. We tested the serum from 13 adult patients with obsessive-compulsive disorder for panels of autoantibodies that serve as markers of autoimmunity in the practice of neurology and internal medicine. We investigated the frequency of neuron-specific autoantibodies [N-type and P/Q-type voltage-gated calcium channel antibodies, type 1 Purkinje cell antibodies, types 1 and 2 antineuronal nuclear antibodies, amphiphysin antibodies, and glutamic acid decarboxylase (65 kDa) antibodies], other organ-specific autoantibodies (muscle acetylcholine receptor-binding antibodies, striated muscle antibodies, thyroid microsomal and thyroglobulin antibodies), and non-organ-specific autoantibodies (antinuclear antibodies, antimitochondrial antibodies, and smooth muscle antibodies) to determine if any of these antibodies might serve as a serological marker for adult OCD or yield evidence of an autoimmune diathesis. Although most of our subjects had onset of OCD before 19 years of age (N = 8) or before puberty (N = 4), the study revealed no humoral evidence of autoimmunity involving the neuron-, organ-, and non-organ-specific antibodies that we assayed.