Singapore remains the easiest place to do business, the World Bank said in a report, with the Asian financial center keeping its title for a sixth straight year.
2011 set a record for regulatory reforms that boost business conditions, among emerging-market and developing economies in particular, the annual "Doing Business" survey of 183 countries found.
After Singapore, rounding out the top five and unchanged from 2010 were, in order, Hong Kong, New Zealand, the United States and Denmark.
Among the major emerging economies, China was middle-ranked at 91st, ahead of Russia (120th), Brazil (126th) and India (132nd).
For the report, the World Bank gathered information on changes in legal frameworks, administrative procedures and technical obstacles in launching or expanding a business.
The Washington-based development lender also drew on public institutions, universities, legal experts and entrepreneurs to measure trading conditions.
Africa overall ranked at the bottom of the list, despite efforts to improve, the World Bank report said.
Dahlia Khalifa, a co-author of the report, told AFP, 2011 saw 125 economies implementing 245 institutional regulatory reforms, an all-time high.
In Sub-Saharan Africa 36 of 46 governments improved the regulatory environment for domestic businesses in 2010/11 -- a record number since 2005, according to the survey.
Chad, however, ranked last. The next four poorest performers, in ascending order, were Eritrea, East Timor, the Democratic Republic of Congo and the Central African Republic.