This is an update from the report-Cardiac Drug and Psychotropic Drug Interactions: Significance and Recommendations-published in this journal in November-December 1999. As mentioned in that article there has been an explosion of new drugs both in psychiatry and cardiology without a sufficient understanding of their potential interactions. Also there is a need for methods to update drug interactions on an ongoing basis. This report describes: 1) examples of actual adverse interactions from clinical cases that move beyond some of the hypothesized contraindications included in the 2000 millennium publication; 2) confirmation of previous adverse interactions reported if they strengthen the earlier findings; 3) listing of new drugs, e.g., sildenafil (viagra) now commonly prescribed by psychiatrists and cardiologists; 4) reports explaining and/or refining mechanisms of adverse interactions; and 5) cautions and important associated phenomenon of either a cardiac or a psychotropic drug, e.g., valproic acid and cases of life-threatening pancreatitis. Methods of publicizing the new knowledge of cardiac drug-psychotropic drug interactions, e.g., the Internet and web sites are described.