Intoxications, as a rule, are related to the medical-legal area; some toxic agents occupy prominent place as the main ones responsible for the occurrence of deaths. In legal medicine, both human and animal, the major challenge faced is the elucidation of the cause of death and the time of death when corpses are found, indicating possible exposure to toxic agents, which are intentionally added most often, in order to cause irreversible damage to the victim. In this context the methods of toxicological analysis involving poisoning are widely studied and disseminated, there are numerous literature reviews on analytical validation processes in the most diverse areas, but reviews of forensic literature are scarce and outdated. Wrong or even unreliable analytical reports can lead to misleading conclusions, culminating in irreparable financial, academic or judicial damages. Since the validation processes are essential in laboratory routines and that forensic analytical methods applied in the legal area are important for the elucidation of xenobiotic intoxication tables, the purpose of this review is to discuss validation processes with a focus on analysis forensic, since the results from this type of analysis must be irrefutable and unequivocal and an error of result