The investigation of drowning constitutes one of the biggest problems in forensic practice. Elevated cardiac troponin I (cTnI) levels in biological fluids have been associated with myocardial damage, whereas increased Mg and Ca levels were found in cases of seawater drowning. The aim of this study was to examine the diagnostic utility of postmortem determination of cTnI, Mg and Ca in the pericardial fluid, in differentiating between cases of seawater drowning related to myocardial injury and those brought about by other causes. This study included 76 cases selected during a 2-year period from medicolegal autopsies. The cases were divided into three groups, according to the cause of death established based on macroscopic and microscopic evidence. The groups were: 1) seawater drowning (n=23), 2) seawater drowning with histological evidence of myocardial infarction (n=28), and 3) myocardial infarction unrelated to drowning (n=25). cTnI was determined with an enzyme immunoassay; Mg and Ca with standard colorimetric assays. Pericardial cTnI levels were significantly lower in group 1 compared to groups 2 and 3. In contrast, pericardial Mg and Ca levels were both significantly higher in groups 1 and 2 compared to group 3. Our results suggest that the postmortem determination of pericardial cTnI levels may be useful in detecting previous myocardial damage as a contributory factor in death from seawater drowning and provide independent confirmation of the usefulness of pericardial Mg and Ca levels for differentiating between seawater drowning and fatal acute myocardial injury unrelated to the former.