Introduction: Growth studies in different countries show that the body size (height and weight measurements) has been increasing over the past one and a half centuries. Study of secular trends in growth is very important. Previous studies in Iran have included small selected groups in different provinces of Iran, so do not provide reliable information regarding overal growth pattern of children in the country. Also, large studies have not been carried out at different intervals where secular changes in growth can be studied.

Methods: Data from two National Health Surveys (1990-91 and 1999) were used to study the secular trends in height and weight of Iranian children over this period.

Results: During the decade of 1990-1 to 1999, on the average, the height of Iranian girls and boys aged 2-18 years increased by 3.6 cm. Also, over this period, on the average, these girls and boys became 2.71 and 3.03 kg heavier, respectively.

Conclusion: Although, median heights and weights of Iranian children up to the age of 15 years are both below the 20th percentiles of NCHS standards, between 15-18 years, median heights and weights lie on the 20th and 25th centiles of NCHS, respectively. Only girls’ median weight between 14-18 reaches the 35th centile. This suggests that the gap might be filled by improvements in nutrition and health services along with the socio-economic development.

Hakim Research Journal 2006 9(1): 1-8.