The Republic of Belarus offers visa-free entry to citizens of 74 countries:
Australia, Austria, Albania, Andorra, Antigua and Barbuda, Barbados, Bahrain, Belgium, Bulgaria, Bosnia and Herzogovina, Vanuatu, Vatican, United Kingdom of Great Britain and Northern Ireland, Hungary, Vietnam*, Haiti*, Gambia*, Germany, Greece, Denmark, Dominica, India*, Indonesia, Ireland, Iceland, Spain, Italy, Canada, Cyprus, China*, Korea (Republic of), Kuwait, Latvia*, Lebanon*, Lithuania, Liechtenstein, Luxembourg, Macedonia, Malaysia, Malta, United Mexican States, Federated States of Micronesia, Monaco, Namibia*, Netherlands, Nicaragua, New Zealand, Norway, Oman, Panama, Peru, Poland, Portugal, Romania, Samoa*, San Marino, Saudi Arabia, Seychelles, Saint Vincent and the Grenadines, Singapore, Slovakia, Slovenia, United States of America, Uruguay, Finland, France, Croatia, Czech Republic, Chile, Switzerland, Sweden, El Salvador, Estonia***, Japan.

*A traveler must carry a valid passport with a valid multiple-travel visa of one of the European Union member States or Schengen Area member states bearing a European Union or Schengen Area entry stamp and also tickets with a return date from Minsk National Airport
**Including persons with Latvia non-citizen status
***Including stateless persons living permanently in Estonia

The whole text of the rules you can find here: http://mfa.gov.by/en/visa/visafreetravel/e0ced19bb1f9bf2c.html