The secular shift between 1974 and 1986 in the menarcheal age of Patiala schoolgirls has been explored. A total of 946 girls of higher and lower social classes (type of school being the criterion) were surveyed, out of which 421 were menstruating at the time of investigations. The median ages at menarche (by probits) of higher social class girls were 12.90 +/- 0.64 years in 1974 and 12.54 +/- 0.13 years in 1986, and of lower social class girls 14.40 +/- 0.47 years in 1974 and 13.65 +/- 0.18 years in 1986. The secular shift per decade in higher and lower social class girls is 0.30 years and 0.63 years, respectively. The social class differences during this period in menarcheal age have decreased.