Background Measuring the distribution of health is a part of assessing health system performance. This study aims to estimate health inequality between different socioeconomic groups and its determinants in Tehran, the capital of Iran.

Methods Self-rated health (SRH) and demographic characteristics, including gender, age, marital status, educational years, and assets, were measured by structured interviews of 2464 residents of Tehran in 2008. A concentration index was calculated to measure health inequality by economic status. The association of potential determinants and SRH was assessed through multivariate logistic regression. The contribution to concentration index of level of education, marital status and other determining factors was assessed by decomposition.

Results The mean age of respondents was 41.4 years (SD 17.7) and 49% of them were men. The mean score of SRH status was 3.72 (range: 1–5; SD 0.93). 282 respondents (11.5%) rated their health status as poor or very poor. The concentration index was −0.29 (SE 0.03; p<0.001). Age, marital status, level of education and household economic status were significantly associated with SRH in both the crude and adjusted analyses. The main contributors to inequality in SRH were economic status (47.8%), level of education (29.2%) and age (23.0%).

Conclusions Sub-optimal SRH was more in lower than in higher economic status. After controlling for age, the levels of education and household wealth have the greatest contributions to SRH inequality.