Sixty-two percent of 975 uveitis patients had a statistically significant elevation in the levels of one or more of three serum immunoglobulins. The percentage of cases of above-normal values was greatest for IgM (43.8%), followed by IgA (34.0%), and then by IgG (11.9%). There was no statistically significant difference in immunoglobulin values obtained for one diagnosis as compared with all others, except for men with HLA-B27. They had a higher percent of elevated IgM values than men with all other diagnoses. Testing for immunoglobulins is of little or no value in the etiologic diagnosis of a single case of uveitis, but may be of value in research studies to better understand its pathogenesis.