Several studies have shown an association between asthma and opiate abuse. This retrospective study aims to analyse the demographic, toxicological, and seasonal differences in asthmatic and non-asthmatic subjects who died of opiates. In addition, the relationship between toxicological levels of opiates and histologic grade of lung inflammation is examined. Deaths from 2013 to 2018 involving opiates as the primary cause of death in Cook County, Illinois (USA) were reviewed. Twenty-six cases of opiate deaths of individuals with a history of asthma and lung histology slides available were identified. In comparison, 40 cases of deaths due to opiates only were analysed. A check-list system for the evaluation of the grade of microscopic inflammation in asthma was developed. We found statistically significant differences between the asthmatics and the non-asthmatics regarding demography (age and race) and toxicology (6-MAM presence). In particular, the “opiate and asthma group” was mainly composed of African-American subjects, in contrast with the “opiate group”, consisting mostly of Caucasian. The mean age was significantly higher in the “opiate and asthma group” compared with the “opiate group”. A greater presence of 6-MAM was detected in the “opiate group” compared with the “opiate and asthma group”. While we expected to find that low opiate levels would lead to deaths in asthmatics and, in particular, that lower opiate concentrations would cause deaths in subjects with higher grades of histologic inflammation, our study suggests that the quantity of drug and the level of inflammation are not statistically significant in the determination of death. We, therefore, recommend histologic examination of the lungs to evaluate for asthma, particularly in suspected low-level opiate-related deaths, to help further clarify any relationship between asthma and opiate use.Copyright © 2020 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.