The distribution of immunoglobulin-producing cells within labial salivary glands from normal individuals (n = 7) and patients with rheumatoid arthritis (n = 10) and systemic lupus erythematosus (n = 9) was studied using morphometric and indirect immunoperoxidase methods. Cell counts revealed a significant increase in the density of IgG cells within glands from both patient groups compared with glands from normal individuals. No significant differences in the density of IgA- or IgM-producing cells between the 3 groups were observed although large individual variations were apparent. Histomorphometric studies showed an increase in the lymphoid compartment and a decrease in glandular elements within glands from the 2 patient groups. When data for all specimens were pooled a significant positive correlation was obtained between the percent area of stromal lymphoid tissue and density of IgG and IgM cells.