To evaluate police and autopsy reports in sudden unexplained deaths in 0-40 year olds. A structured, blind review of police and autopsy reports send to a cardiac genetic service from before (February 2006-December 2007) and after (January-December 2009) new best practice guidelines were introduced in Australia and New Zealand was performed. The reviews focused on reporting on: (1) presentation and clinical history, (2) cardiac autopsy, (3) histological tests and toxicology, and (4) detailed examination of coronary arteries. 110 reports were evaluated against the guidelines. 100 % reported location, 95 % activity at time of death, and 84 % some clinical history. Less than 25 % reported on family history, presence/absence of illicit drugs or alcohol, recorded a possible arrhythmic trigger, or history of fits/faints or collapses. Over 95 % listed heart weight, valvular examinations, pulmonary and some myocardial histology. Less than 50 % commented on septal, LV (left ventricle) and RV (right ventricle) wall thickness. Less than 50 % mentioned site of histology samples, or gave specific description of LV or RV histology or conduction system. Toxicology was not mentioned in a third. Histology of coronary arteries was described in only 18 %. Post guidelines reporting increased in some areas, e.g. in 1-40 year olds: antecedent symptoms (22-61 %), number and location of histology samples (0-47 %), and histology of coronary arteries (6-50 %). Most police and autopsy reports fall short of best practice guidelines. They have improved somewhat after the new guidelines were introduced, but need to be more consistent and particularly need to include significant negative findings.