Transilial bone biopsies were obtained from 34 healthy postmenopausal women following in vivo fluorochrome labeling. Stained and unstained undecalcified sections were evaluated using a Merz grid. Standard histomorphometric data from cancellous bone tissue were collected and the results were evaluated and presented as variables commonly used in bone histomorphometry. The normal ranges, medians, means, and standard deviations for the group of 34 are presented in tabular form for structural, surface, basic dynamic, and derived dynamic data. Similar data for individuals grouped by ages 45-54, 55-64, and 65-74 are also presented. Secular trends for the whole group are evaluated. The structural and surface data are not much different from previous reports of sudden-death accident victims, when methodologic differences are considered. The mineral apposition rate (MAR) was 0.53 +/- 0.08 micron/day, similar to previous reports in cancellous bone, but one-third less than in cortical bone. MAR showed a marked decline with age. In contrast, the extent of tetracycline-labeled surfaces varied widely without a secular trend. Double-label surface (dLS/BS) ranged from 0.5 to 8.0% and single-label surface (sLS/BS), from 0.5 to 10.5%. Mineralizing osteoid surface (MS/OS) varied from 2 to 64%. Using only double-label surface to represent mineralizing surface, volume-based bone formation rate (BFR/BV) ranged from 0.7 to 28%/yr, and the remodeling period (Rm.P) varied from 0.28 to 4.5 years. Calculations using other representations of mineralizing surface [double plus one-half single label (MS/BS"); all label (MS/BS')] are also presented. These bone histomorphometric data are important because: (1) they come from a cohort of living subjects that was recruited solely for the purpose of establishing normal bone histomorphometry; (2) they represent the age range of patients with postmenopausal osteoporosis; and (3) they markedly expand the bone histomorphometric database of healthy persons given in vivo fluorochrome labeling prior to transilial biopsy.