Military personnel deployed to the Persian Gulf War have reported a variety of symptoms attributed to their exposures. We examined relationships between symptoms of respiratory illness present 5 years after the war and both self-reported and modeled exposures to oil-fire smoke that occurred during deployment. Exposure and symptom information was obtained by structured telephone interview in a population-based sample of 1,560 veterans who served in the Gulf War. Modeled exposures were exhaustively developed using a geographic information system to integrate spatial and temporal records of smoke concentrations with troop movements ascertained from global positioning systems records. For the oil-fire period, there were 600,000 modeled data points with solar absorbance used to represent smoke concentrations to a 15-km resolution. Outcomes included respiratory symptoms (asthma, bronchitis) and control outcomes (major depression, injury). Approximately 94% of the study cohort were still in the gulf theater during the time of the oil-well fires, and 21% remained there more than 100 days during the fires. There was modest correlation between self-reported and modeled exposures (r = 0.48, p < 0.05). Odds ratios for asthma, bronchitis, and major depression increased with increasing self-reported exposure. In contrast, there was no association between the modeled exposure and any of the outcomes. These findings do not support speculation that exposures to oil-fire smoke caused respiratory symptoms among veterans.