Ig-producing cells were quantified by paired immunohistochemical staining in saline-extracted and paraffin-embedded normal tissue specimens from human parotid (ten) and submandibular (seven) salivary glands. The density of such cells (number/mm2 of 6 micron thick tissue section) was significantly higher in the submandibular than in the parotid gland (P less than 0.005), but the Ig-class distribution was fairly similar. The mean percentage class ratios for IgG, IgA, IgM and IgD cells in the parotid were 4.5:86.5:5.9:3.1, and in the submandibular gland 3.7:86.9:7.9:1.6. In the parotid gland of a patient with selective IgA deficiency the same class ratios were 27:0:20:53. Thus, the IgA cells were especially replaced by IgD cells. In normal glands most of the IgA (80-93%), IgM (99-100%) and IgD cells (81-95%) were J-chain-positive; this was likewise true for a substantial proportion of the IgG cells (32-46%). Of additional interest was the finding that in the IgA-deficient parotid gland, 99% of the numerous IgD cells and 86% of the increased number of IgG cells contained cytoplasmic J chain. IgE-producing cells were virtually absent from the IgA-deficient as well as from the normal salivary glands.