Firefighting is a unique job with contradictious demands that expose firefighters to many well documented causal factors of sleep debt, but no studies in Iran and only a few worldwide studies have investigated their sleep quality while sleep problems may lead to catastrophes especially in critical service workers. The aim of this study is to evaluate sleep quality and its related factors among a sample of professional Iranian firefighters.Using simple random sampling method in a cross-sectional study, 427 personnel of fire and rescue service were invited. They completed the Persian version of Pittsburgh Sleep Quality Index (PSQI) and a data collection sheet about their demographic and occupational features during an individual face to face interview in central office and firehouses throughout Tehran. Response rate was 88.7%.The mean ± SD global PSQI score was 7.97 ± 3.77. Sleep latency was the component of PSQI with the greatest degree of abnormality. 69.9% of participants were poor sleepers. Interestingly, we found no significant differences between sleep quality of shift workers and non shift workers. Using multiple logistic regression analysis, only having another job, smoking and years of job experience were predictors of poor sleep.In comparison with adult population of Tehran, sleep quality deterioration is notably more common in Tehran firefighters which require health promotion interventions to prevent its serious adverse outcomes.