As of 15 April 2015, the Asian Infrastructure Investment Bank (AIIB) consists of 57 Prospective Founding Members.
Asian members:
China
Australia
Azerbaijan
Bangladesh
Brunei
Cambodia
Georgia
India
Indonesia
Iran
Israel
Jordan
Kazakhstan
Kuwait
Kyrgyzstan
Laos
Malaysia
Maldives
Mongolia
Myanmar
Nepal
New Zealand
Oman
Pakistan
Phillippines
Qatar
Russia
Saudi Arabia
Singapore
South Korea
Sri Lanka
Tajikistan
Thailand
Turkey
United Arab Emirates
Uzbekistan
Vietnam
Hong Kong will also be an AIIB member, though whether it will be represented independently or as part of China has yet to be decided.
Non-regional members:
Austria
Brazil
Denmark
Egypt
Finland
France
Germany
Iceland
Italy
Luxembourg
Malta
Netherlands
Norway
Poland
Portugal
South Africa
Spain
Sweden
Switzerland
United Kingdom