On biopsy material, differences in the degree of conjunctival inflammation and fibrosis between topically treated glaucoma patients and age matched controls, were examined histologically. Eighteen patients with primary glaucoma underwent goniotrephinations, because maximal medical therapy had failed. The patients had received at least two types of topical anti-glaucoma drugs for at least 12 months (mean 46 months). The control group consisted of 18 age-matched control patients without glaucoma, who had received no topical therapy. These patients underwent cataract surgery or squint surgery. Biopsies were taken from the infero-temporal bulbar quadrant with a biopsy forceps. The specimens were fixed while stabilized on a rubber support to exclude any major shrinkage. Specimens were analyzed by light microscopy for the content of inflammatory cells (plasma cells, lymphocytes, polymorphs, macrophages and mast cells), goblet cells and fibroblasts. No significant difference in the histologic parameters between the two groups could be demonstrated. The study suggests that topical treatment for periods up to 4 years with anti-glaucoma drugs does not induce morphological signs of inflammation and fibrosis of the conjunctiva.