Toxicokinetics is an essential step in clinical toxicology. The methodology is based on the same parameters which are used in pharmacokinetics. However, the interpretation and the aims are different. For each toxicon, the interpretation of kinetic data needs to take account of the spontaneous toxicokinetics, the factors of variation, the relationship kinetic data and symptoms, the severity and prognosis criteria. The evaluation of treatment has to take account of the global kinetic action of the toxicon during the intoxication and the effects on the symptomatology. The mechanism of toxicity, is an essential item in the interpretation of toxicokinetic data. By the exact knowledge of toxicokinetics, it is possible to determine for each toxicon, the relevant parameters which will be of use in clinical practice.