BACKGROUND:
Due to geographical, racial, nutritional and socio-economical effective factors in pubertal age, assessment of pubertal stages should always be based on native, up-to-date and reliable references data from the same background population. This study is conducted to determine the age of different pubertal stages in school-age girls of Isfahan.

METHODS:
This was a cross-sectional study of 5.5 to 17 years-old girls of Isfahan among 3204 population in 2006. The data was collected through the multistage cluster probability sampling basis. Pediatric endocrinologist evaluated pubertal stages by inspection and palpation according to Tanner staging. Weight, height and skin fold thickness were measured and recorded. The subjects were asked about menarche occurrence and the age of its onset if there is any. The difference between mentioned factors and different pubertal stages were calculated and analyzed by Covariance statistical estimation.

FINDINGS:
The mean age and standard deviation of thelarche, pubarche and menarche was 10.46±1/37, 11.15±1/30 and 12.56±1/15 year, respectively. Different pubertal stages have a significant relation to BMI and skin fold thickness (p<0.01). In the population under study, the puberty onset is considered sooner than 7.72 years-old as precoious puberty and later than 13.8 year-old as delayed puberty.

CONCLUSION:
It is concluded that thelarche and menarche age in girls living in Isfahan is higher than some other countries like USA, whereas menarcheal age is the same as other studies in Iran.

KEY WORDS:
Puberty, thelarche, pubarche, menarche