The aim of this study is the estimation of biological effects of changes of economic conditions in Poland in 1967-2001. Rural girls aged 9.5-18.5 years were studied in 1967, 1977, 1987 and in 2001. The stratification of villagers (farmers, farm-workers and non-farmers) was based on the source of their family income. Age at menarche (AM), body height and weight were used as biological indicators of living conditions. During the decade 1967-1977, while a relatively good economic situation prevailed in the country, AM decreased (accelerated) by 0.64 years and distinct secular trends in height and weight were noted. During the decade 1977-1987, years of economic crisis, secular trends were arrested and age at menarche increased (decelerated) by 0.11 years. The study, repeated in 2001, showed positive secular trends in body height and a decrease (acceleration) in AM (0.24 years per decade), but in daughters of farmers, the AM decrease was twice as high as in non-farmer families. The latter group experienced acute unemployment after the political and economic system transformation (1989) AM appeared earliest in daughters of non-farmers, and latest in those from farmer families.