The prevalence of glaucoma was studied using material from the Registry of Right to Free Medications, completed by the Social Insurance Institution of Finland in 1985. A total of 31,981 patients (10,022 males and 21,959 females) received free medication for glaucoma in 1985. Total crude glaucoma prevalence in Finland in 1985 was 0.67%, calculated for the total population (all glaucomas) according to data from this registry. The crude prevalence for those of 40 years of age and over, was 1.7% and for those of age 70 years and older, 6.1%. Age adjusted prevalence showed a female excess of cases with a male-female ratio of 1/1.3. The incidence of different types of glaucoma was studied using the Hospital Discharge Registry for the years 1973-1982. For this 10-year period, a total of 48,864 patients with glaucoma and 10,614 glaucoma suspects were found in a compilation based on an International Classification of Diseases (8th edn.) code number. Of all adult glaucomas, 67% were primary glaucomas, while 33% were secondary glaucomas. An increase in the incidence of glaucoma was noted during the 10-year period, especially for the chronic simple and capsular glaucoma groups. Females were at higher risk for chronic simple, acute angle-closure, capsular and chronic angle-closure glaucoma; whereas, males were at greater risk for other types of secondary glaucomas. The patients with secondary glaucoma were the youngest (mean age 53.5 years in males, and 60.3 years in females), while the patients with capsular glaucoma were the oldest (mean age 71.9 years in males, and 72.8 in females).