Objectives Suicide is a major global health problem imposing a considerable burden on populations in terms of disability-adjusted life years. There has been an increasing trend in fatal and attempted suicide in Iran over the past few decades. The aim of the current study was to assess overall, gender and social inequalities across Iran’s provinces during 2006–2010.

Design Ecological study.

Setting The data on distribution of population at the provinces were obtained from the Statistical Centre of Iran. The data on the annual number of deaths caused by suicide in each province were gathered from the Iranian Forensic Medicine Organization.

Methods Suicide mortality rate per 100 000 population was calculated. Human Development Index was used as the provinces’ social rank. Gini coefficient, rate ratio and Kunst and Mackenbach relative index of inequality were used to assess overall, gender and social inequalities, respectively. Annual percentage change was calculated using Joinpoint regression.

Results Suicide mortality has slightly increased in Iran during 2006–2010. There was a substantial and constant overall inequality across the country over the study period. Male-to-female rate ratio was 2.34 (95% CI 1.45 to 3.79) over the same period. There were social inequalities in suicide mortality in favour of people in better-off provinces. In addition, there was an increasing trend in these social disparities over time, although it was not statistically significant.

Conclusions We found substantial overall, gender and social disparities in the distribution of suicide mortality across the provinces in Iran. The findings showed that men in the provinces with low socioeconomic status are at higher risk of suicide mortality. Further analyses are needed to explain these disparities.