•Older cases were more likely die due to combined drug toxicity/disease.•Older cases were more likely to have chronic pain.•Older cases were more likely to have evidence of a sudden collapse.•Older cases appared to have shorter survival times.•Older cases had more extensive heart, lung, and liver disease. The age of people who use illicit opioids has increased, with a clinical picture of accelerated ageing. The study aimed to determine, stratified by age: 1. The circumstances and characteristics of heroin-related toxicity deaths in Australia, 2020–2022; 2. The toxicological profile and autopsy findings; 3. The proportion of cases in which blood 6-acetyl morphine (6AM) was detected, as a measure of survival time. Retrospective study of 610 cases of fatal heroin-related drug toxicity in Australia, 2020–2022. Cases were stratified as: <30 years, 30–39 years, 40–49 years, ≥50 years. Compared to the youngest group, those aged ≥50 years were more likely to have a history of chronic pain (12.4 v 3.3 %), to have their death attributed to combined drug toxicity/disease (20.1 v 3.3 %), and to have evidence of a sudden collapse (21.3 v 11.1 %). There were no differences in free morphine concentrations or glucuronide concentrations. Compared to the youngest group, however, the two older groups were significantly more likely to have 6AM present in blood, a proxy measure of a shorter survival time (52.0, 55.2 v 34.5 %). Compared to the youngest group, cases aged ≥50 years were more likely to be diagnosed with cardiomegaly (44.0 v 16.7 %), coronary artery disease (46.0 v 15.0 %), emphysema (35.0 v 5.1 %), hepatic steatosis (15.4 v 3.4 %), hepatic fibrosis (17.6 v 3.4 %), and cirrhosis (19.8 v 0.0 %). Older cases of heroin overdose had more extensive heart, lung, and liver disease, and appeared more likely to have shorter survival times.