In May, 2004, the border of the European Union (EU) will shift eastward such that the new frontier will be made up by Ukraine, Belarus, and a considerably longer Russian border. Here, we discuss three issues: first, the factors that have contributed to the growth of communicable disease in Russia, Ukraine, and Belarus; second, how public health systems have responded to these challenges; and third, the implications for the EU as a whole. Since the break-up of the Soviet Union, Russia, Ukraine, and Belarus have witnessed substantial political, social, and economic changes. These events have been reflected in changes in the epidemiology of communicable diseases, including tuberculosis and HIV (ie, HIV-1). Moreover, public health systems, rooted in Soviet traditions, are struggling to respond effectively to the challenges of resurgent infectious diseases, such as tuberculosis, and newly emergent challenges such as HIV. The changing patterns of communicable diseases east of the EU's new border has implications for how the EU aids the strengthening of public health systems east of the new frontier. Transborder spread of communicable diseases also challenges communicable disease control systems within the EU. Concerted action is needed by member states and the EU, building on models of cooperation between institutions that have been successful in areas beyond health, if public health systems are to meet the emerging challenges to communicable disease control.