The thesis investigates the efficiency of depository institutions in Austria, Bulgaria, Croatia, Serbia and Turkey between 2003 and 2006. Four of these countries switched from a planned to a market economy in the early 1980ies. These are contrasted with Austria. High coverage ratios are ensured by using data published by the relevant regulatory authorities. Data envelopment analysis yields higher efficiency scores in all but one country when deposits are treated as output. This implies that banks see deposits as products they offer to their customers and which they do not attempt to minimize. While in some countries improvements in efficiency can be detected against an inter-temporal single-country efficiency frontier, no overall efficiency improvement against a common regional frontier can be identified. Results of a Malmquist Index analysis are also inconclusive for the region as a whole, although technological improvement can be shown for Austria between 2004 and 2005. When data is grouped by country, Austria and Croatia emerge as most and Serbia and Bulgaria as least efficient markets. An interesting pattern emerges when DMUs are grouped by category (savings, cooperative and universal banks) and country. It can then be seen that savings and cooperative banks show comparably low efficiency in Austria but comparably high scores in Serbia and Croatia. For universal banks, this pattern is reversed. (author's abstract)