This volume consists of the first fruits of the collaboration between the publishing house DOCUMENTA UNIVERSITARIA and the BORJA INSTITUTE OF BIOETHICS on specific areas of bioethics, which constitute this collection. This first offering, therefore, is the result of a multidisciplinary and collective endeavour, with contributions from I. Abbas, F. Antoñanzas, J. Colom, A. García-Altés, J. M. Ollé, J. Rovira and F. Torralba and the collaboration of the General Directorate for Drug Addiction and AIDS of the Catalan Autonomous Government (Direcció General de Drogodependències i SIDA de la Generalitat de Catalunya). The reflections and scientific analysis that constitute the first part of this book constitute the essential part of the work from the perspective of the Borja Institute of Bioethics. These contributions ought to be sufficient to achieve the goal of looking after one's own health and rejecting a lifestyle that does not contribute to preserving it. These evaluations are made without taking into account whether those changes in health that result from certain attitudes or an unhealthy lifestyle have a specific economic cost. The second part of the book, on the other hand, incorporates as examples two studies related to the economic aspects of the consumption of tobacco and other drugs. The study undertaken by Joan Rovira and Ismail Abbas and entitled "Els costos dels hàbits de vida no saludables; el cas del tabaquisme a Catalunya" was made possible by the financial assistance of the Borja Institute of Bioethics, while their study on the "Avaluació del cost social del consum de drogues il·legals a l'Estat espanyol" was made possible by the General Directorate for Drug Addiction and AIDS of the Department of Health and Social Security of the Catalan Autonomous Government. This work is based on a broader study carried out by the Catalan Agency for Health Technology Assessment and Research (Agència d'Avaluació de Tecnologia i Recerca Mèdiques) in collaboration with the General Directorate already mentioned, entitled "An assessment of the social cost of the consumption of illegal drugs in Catalonia and Spain". This work will be published by the Department of Health and Social Security of the Catalan Autonomous Government. The authors of this study are Anna Garcia-Altés from the Health Services Research Institute (Fundación Instituto de Investigación en Servicios de Salud) and the New York City Department of Health and Mental Hygiene, Josep M. Ollé and Joan Colom from the General Directorate for Drug Addiction and AIDS of the Department of Health and Social Security of the Catalan Autonomous Government, and the lecturer Fernando Antoñanzas from the Department of Business Studies and Economics at the University of La Rioja.