The number of cells in the human trabecular meshwork was assessed for counting meshwork cell nuclei in semithin Araldite sections cut in the meridonal plane. The counts of nuclei decreased with increasing age and the decrease was associated with all regions of the meshwork. The appropriate regression equation and a mean length for meshwork nuclei was used to estimate cell numbers. At 20 years of age the estimated cell number for the whole meshwork was 763,000 which decreased to 403,000 cells by 80 years with a loss rate of 6,000 cells per year.