Naturalisations dropped 16 percent in 2008, the lowest level since German reunifcation in 1990, the Federal Statistics Office said in a press release Friday.
The Wiesbaden-based statistical service reported said 94,500 foreigners became German citizens last year, 18,600 fewer than in 2007.
Naturalisations peaked in 2000, after the enactment of a new citizenship law. Then, 186,700 people got German passports, almost double last year's number.
The former East German state of Mecklenburg-Western Pomerania saw a 41 percent drop in the number of naturalisations that took place there in 2008. Hamburg recorded a 31 percent fall, and naturalisations fell 24 percent in the sourthern economic dynamo of Bavaria.
One of Germany's poorest states, Saxony-Anhalt in eastern Germany swam against the national trend: Naturalisations there rose five percent last year.
The naturalisation figures were unearthed after parliamentary inquiry last month about a controversial new German-language test that is now required of citizenship
24,500 Turks applied for German citizenship in 2008, making them the biggest group of naturalised citizens with 25 percent of naturalisations.
Applicants from the former Serbia and Montegro and Poland came in second place, with 6,900 naturalisations from both. 4,200 refugees from Iraq received German citizenship, a slight increase from past years.
The largest declines in German naturalisations came from the Ukraine, where naturalisations fell 56 percent, and Russia, which fell 40 percent from the previous year.