In this paper, the distribution and redistribution of the amphetamine derivative, 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) is brought into focus. Animal experimental data were compared with internationally reported MDMA-related human fatalities: in general, these turned out to be parallel with each other. Due to its inherent properties (e.g. significant volume of distribution), MDMA is liable to postmortem redistribution. Indeed, very high concentrations have been found in cardiac blood and tissues located centrally in the body (blood-rich organs such as lungs and liver in particular). This confirms that post-mortem redistribution due to diffusion from higher to lower concentration can easily take place, mainly at longer post-mortem intervals and when putrefaction occurs. Therefore, we can conclude that for post-mortem quantitation of amphetamine and derivatives, and MDMA in particular, peripheral blood sampling (e.g. femoral vein) remains compulsory. However, if the latter is impossible, MDMA quantification in a few alternative matrices such as vitreous humour and iliopsoas muscle may provide additional information to come to a reliable conclusion. Furthermore, it should be stressed that--at present--it is impossible to estimate the individual susceptibility to the various possible adverse effects of MDMA, which implies that it is impossible to provide a "safe" or "therapeutic" blood MDMA level. Therefore, in current forensic practice, the post-mortem pathological and toxicological findings should form an entity in order to draw a well-grounded conclusion.