Aim: To evaluate the histological changes and immune response of conjuctiva in patients (pts) with lo S.S. Materials and Methods: We studied conjunctiial biopsies from 15 pts with I0 S.S. and 2 normal controls using 1) paraflfn section screening for the quality of conjunctival epithelium (CE), the number of goblet cells (GC) and the degree of inflammation, 2) Mo-abs and Pabs to: Tlymphocytes, T4, NK cells, &lymphocytes, K and A light chain and MHC antigens class II (HLA DR) and I (br microgl), 3) frown sections stained with Mo-ab to TS and direct I.F. for detection of Ig’s (IgA, IgM, IgM) and complement (C3, Clq, Cu) deposits. Results: The thickness of CE was focally or diffusely diminished in 9/15 pts. Desquampltton of the cells was found In 11/15 pts. Nine pts had a great reduction and 6 moderate reduction in number of GC. Two had normal numbers. Inflammation was severe in 2, moderate in 4, low in 2 and absent in 2 pts. A good correlation of findings between lip and conjuctiva biopses was observed in E/IO pts. In 13 pts with inflammation, T cells predominated, T4:TE ratio was about 2.3:1, NK cells were rare and plasma cells (found in 7/15 pts) were K+ > A+. In 4 cases uneven staining of CE for HLA-DR was found. Five cases showed mainly epithelial and 2 both CE and endothelial staining for brmicr. In 5/13 cases granular deposition of compl (C3 and/or C4) with Ig’s (IgM/IgG) in capillary wall was found. Controls were negative. Conclusion: In I0 S.S. 1) the predominant cell of the conjunctival inflammation is T-lymphocyte, 2) conjunctival epithelial cells may show increased expression of MHC class I and aberrant expression of class II and 3) capillary immune complex deposition can be also found.