We studied 263 eyes of 141 normal subjects, 33 men and 108 women, including 129 Finns and 12 Ibero-Americans, with the age ranging between 12 and 89 (mean 43.0 +/- 20.4) years using the Kowa FC-1000 laser flare cell meter. The mean photon count/ms was 4.5, it was 3.1 in the age groups of 10-19 years and 11.5 in the age group of 80 years or over; the increase with age was statistically significant (p = 0.0001). There were no significant differences in the photon count/ms between right and left eyes (p = 0.75), between sexes (p = 0.61), or between Ibero-Americans and age-matched Finns (p = 0.62). The mean cell count was 1.1 and there were no significant changes between the right and left eyes (p = 0.56) or between different age (p = 0.38), sex (p = 0.32) and race (p = 0.64) groups. There were no significant differences in the mean photon count/ms (p = 0.97) and cell counts (p = 0.35) between the first and second measurements 5 min later. There was no subject-within variability after 24 h and 7 days in the flare (p = 0.95) and cell counts (p = 0.89).