In this article, relevant recent changes in the diagnosis and therapy of infectious diseases are reviewed. Several new diagnostic tools for the quantification of viral DNA and RNA have been developed in the last years (PCR-based and related methods). A number of new antiviral agents has been licensed for the treatment of different viral infections. The clinical management of viral infections has dramatically changed with these tools and agents. Especially morbidity and mortality of HIV-infected patients have both been reduced by antiretroviral combination therapy. With rising rates of antibiotic resistance in gram-positive bacteria, therapy of infections with these agents has become increasingly difficult. A number of new antibiotic agents for the treatment of these infections have been developed and licensed.