This article has briefly summarized the physiologic effects, pharmacokinetics, adverse effects, drug interactions, and methods of analysis for the newer cardiac agents. Methods of analysis for these newer agents are primarily chromatographic types, such as gas-liquid or high-pressure liquid chromatography. Conspicuously absent from methods of analysis for these agents are the newer immunologic methods such as RIA or enzyme-linked assays. This deficiency in methodology is due to several factors. Cross-reactivity between metabolites and parent compounds is often a problem with antibody-based assays, and several of these agents have metabolites that reach concentrations equivalent to that of the parent drug. Several of the newer antiarrhythmics are structurally related not only to each other but also to older agents such as lidocaine. Overcoming this cross-reactivity would be necessary before these assays could be used in patients being converted from intravenous lidocaine to the newer oral preparations. With the development of monoclonal antibody techniques, the need for close therapeutic monitoring of several of the drugs, and the increased emphasis on restraining costs in the clinical laboratory, the newer immunologic methods may soon be introduced in the United States.