This study has investigated the presence and distribution of B cells, T cells and T-cell subsets within labial glands of patients with primary Sjogren's syndrome (n = 9) and secondary Sjogren's syndrome associated with rheumatoid arthritis (n = 8) using a sequential double immunoperoxidase technique and true colour image analysis. The composition of the inflammatory infiltrates was similar in glands from both patient groups. B cells were normally present within large foci with few detected in diffuse infiltrates such that the ratio of T:B cells in foci (2.4:1) was significantly lower than in diffuse infiltrates (7.3:1; P less than 0.001). In all infiltrates helper T cells (CD8-, CD3+) predominated over suppressor/cytotoxic cells (CD8+, CD3+; 2.7:1). Analysis of primed (CD45RA-, CD45RO+) and naive (CD45RA+, CD45RO-) CD8- T cells showed that the ratio of the primed to naive subset was significantly higher in focal (4.2:1) compared to diffuse (1.5:1; P less than 0.001) areas of lymphoid infiltration. These results indicate that the focal lymphocytic infiltrates characteristic of Sjogren's syndrome contain B cells associated with a T-cell population consisting predominantly of primed CD8- helper T cells. This latter population may be responsible for upregulating glandular B-cell activity in Sjogren's syndrome.