Background and Aim: The present article attempts to define the current trend for age at first marriage, based on the nationwide Health Survey of 1999 and using the Brass model.

Material and Methods: The national Health survey was conducted in 1999 and involved 1/1000 of the total population, selected via cluster sampling (clusters of 8 households each).

The sample used for the present study consisted of 16000 women aged 15-49, including 3026 women in Tehran province. Variables used for analysis were current age, marital status, age at first marriage and residential area (urban/rural). The mean age at first marriage for married women was 17.8 years (sd=3.7) for the whole country, and 18.2 years (sd=3.7) for Tehran province.

Results: The Brass model fitted to the data revealed a significant decreasing trend for the proportion of married women in all age groups, especially in the 15-19 year-old category.

Conclusion: This obviously indicates an upward trend for age at first marriage.