In June 2001, the European Commission passed a new Directive for tobacco products, which, in addition to other regulations, obliges the manufacturers and importers of tobacco products in the EU to disclose the ingredients used in their products and also to submit data on the toxicological properties of these ingredients in burnt and unburnt form. The idea of monitoring and regulating additives used for tobacco products is rather old. Almost 200 years ago, C.F. Hareless in Nuremberg [cited in P.J. Schneider: Über die Gifte; Tübingen, 1821] established 12 rules for the correct use of ingredients in manufacturing tobacco products and vinegar. These rules cover almost all aspects for a consumer-friendly, responsible and safe use of additives for tobacco products and could, therefore, have served as an example for the present EU Tobacco Directive. For instance, Hareless states in Rule 4 that the manufacturer submits to the health department the prescriptions of all added ingredients in snuff and smoking tobacco. It was also planned that the responsible authority can perform unannounced “empirical” and “chemical” tests of the finished products (Rules 7 and 8). Although these rules call for strong regulation of ingredients, they do not challenge the use of additives in snuff and smoking tobacco because ingredients may contribute to the quality, acceptability and also the safety of the product. The Directive rightly asks for toxicological data of ingredients in burnt form, in order to be sure that the use of additives does not increase the biological effects of tobacco products. The review of Paschke, Scherer and Heller in this issue of BeiträgezurTabakforschung International/Contributions to Tobacco Research has compiled data from published papers on the toxicological effects of ingredients in burnt form. The authors did not intend to evaluate the presented methods and data, therefore, this review is more a reference work rather than a scientific article. It is obvious from the material presented that there is a lack of Standard Methods for testing the toxicological properties of tobacco ingredients in burnt form. The huge number of different approaches presented in this review points to the difficulties in defining suitable methods for this purpose. Despite these limitations, it is justified to state that the data so far available give no evidence that ingredients in use today increase the toxicity of tobacco smoke.