This article reviews the literature related to the "drug lag" issue, i.e., the issue of whether important new drugs are introduced relatively late, or, in certain cases, are introduced at all, in a particular country. The literature can be divided into two main parts: studies primarily related to the delay in introduction of new drugs and studies primarily related to the number of introduced new drugs. Most studies have found the United States, Sweden, and Norway to have a long delay in the introduction of new drugs. The United Kingdom and (West) Germany in general have the shortest delay. There are also large differences in the number of introduced new drugs. In most studies, the United States and Norway have introduced far fewer new drugs than any other industrialized country. In general (West) Germany, France, the United Kingdom, and Italy have introduced the largest number of new drugs. One of the reviewed studies presented a relationship between regulatory processing time and delay in introduction. Another study found an increasing influence of regulatory stringency on the number of introduced new drugs in a country. If a country's aim is to decrease the delay in introduction and/or to increase the introduction of important new drugs, a review of the local regulatory agencies and the regulations seems worthwhile.