A sample of 114 girls from low-middle and highest socioeconomic levels of Istanbul were followed at 6-month intervals for 7-9 years during adolescence. Results pertaining to age of menarche and its relationship to growth and maturation are presented. No significant difference was found for the occurrence of menarche in relation to season. The age of menarche was 6.6 months earlier in daughters compared to their mothers, but the variation between mothers and daughters was great. In the lower socioeconimic class, age of menarche was significantly later, 12.5 years in the high and 13.4 years in the lower class. Later menarche in the lower class was related to lower rates of growth in stature and weight, and of skeletal and sexual maturation. There was no significant correlation between age at menarche and stature and weight attained at menarche. Those with a faster rate of growth reached menarche early and the height velocity continued to be faster. The median stages of secondary sexual characteristics at menarche were 4 for breast and pubic hair, and 3 for axillary hair. The stage of development at menarche did not differ significantly with age of menarche and social class. Menarche occurred 2.4 years after the appearance of pubic hair, 2.0 years after the appearance of the breast bud, and 1.4 years after the appearance of axillary hair, and the ages at which the secondary sexual characters appeared correlated significantly with the age of menarche. Skeletal age at menarche was 13.0 +/- 0.69 years. Age of menarche correlated best with the age at which fusion of the second and first distal phalanges occurred. The percentage of adult height attained at menarche correlated significantly with the age of menarche. Regression equations and standard errors are presented to aid in the prediction of the age at menarche from other variables related to menarche. (C) 1995 Wiley-Liss, Inc.