Sudden cardiac death due to underlying coronary artery thrombosis is one of the leading causes of death. However, in a significant percentage of individuals who died suddenly, no indication of myocardial infarction is found during post-mortem examination, especially when the time interval between appearance of symptoms and death is short. In the present study, we have evaluated certain nuclear morphometric parameters, such as, minimum, maximum, mean and standard deviation of perimeter and area in 20 individuals who died of coronary artery thrombosis, within 1 h from symptoms onset. Furthermore, the above parameters were compared with those of a control population of 20 individuals whose sudden death was caused by traffic accidents. Statistical elaboration of the results by means of t-test, Mann-Whitney (U-test) and analysis of covariance (adjusting for age), showed a statistically significant difference for all variables except for the minimum area. With stepwise discriminant analysis method, the mean perimeter was selected as the best predictor of cardiac death. Mean perimeter achieved a correct reclassification percentage (based on Fisher's linear discriminant function) of 92.5% (85% and 100% for cases and controls, respectively). Moreover, by applying the cut-off of 172 microns, we could identify the individuals who died suddenly because of coronary artery thrombosis with a specificity of 100% (sensitivity 85%, P < 0.001). Our results show that nuclear morphometry of the myocardial cells is a reliable diagnostic tool for the diagnosis of coronary thrombosis based lesion in cases of sudden death, even when methods trying to verify the presence of infarction fail to do so.