Some studies have shown a connection between asthma deaths and opiate abuse, but the process in which opiates exacerbate asthma is still unclear. Opiates may impair judgment during an acute asthma attack, leading to inadequate treatment. Alterations in mental status may increase aspiration risk. Some studies have also demonstrated an opiate-induced bronchoconstriction. In the present study, data on opiate deaths in the Department of Forensic Sciences of Sapienza University of Rome and in Cook County Medical Examiner’s Office in Chicago (USA) have been collected. A comparison was performed between the opiate users who had a history of asthma and the opiate users who did not, regarding demographic, anamnestic, seasonal, autopsy, histological and toxicological findings. A histological grading of asthma changes was also performed. A history of asthma was found in 78 out of 855 cases of opiate deaths (9.12%). The majority of people who died due to opiate intoxication and had a history of asthma were males and African-American. Among asthma cases, the levels of morphine in blood ranged between 23-1,740 ng/ml (Mean: 209.51 ng/ml), the levels of blood 6-MAM ranged between 12-280 ng/ml (Mean: 80.6 ng/ml) and the levels of blood codeine ranged between 24-34 ng/ml (Mean: 26.6 ng/ml). Regarding the grading of asthma, we found 32 cases with severe asthma, 19 with moderate asthma and 27 with mild asthma. We randomly selected 80 opiate deaths without a history of asthma. The levels of morphine in blood ranged between 1,115-5,280 ng/ml (Mean: 3,450.89 ng/ml), the levels of blood 6-MAM ranged between 70-460 ng/ml (Mean: 321.1 ng/ml) and the levels of blood codeine ranged between 23-52 ng/ml (Mean: 45.7 ng/ml). Preliminary statistical analyses revealed that the levels of blood morphine were significantly higher in non asthma cases compared with asthma cases. These findings may support the hypothesis that the quantity of morphine needed to cause death in asthmatic can be lower than the quantity of morphine needed to cause death in non asthmatic: anatomic and physiologic changes of asthma can play a role in deaths due to opiate, maybe determining a higher susceptibility to the effects of these substances (bronchoconstriction, respiratory depression, etc)