Guajará-Mirim (pop. 29.000, 2004) is in the western part of the state of Rondônia in Brazil. It is separated from Bolivia by the Mamoré River.

It is the southern terminus of former railroad Estrada de Ferro Madeira-Mamoré.

Buses go to Porto Velho, 5-7 hours away (333 km to the north).

Small boats take you on the five minute trip across the river into the Bolivian border town of Guayaramerín.

The town is small enough to reach most places by foot.

• Guaporé Nature Reserve
• The 18th-century fort of Príncipe da Beira is three days by boat from Guajará-Mirim. It can also be reached by road. Take BR-364 to AM-429, which goes to the town of Costa Marques.
• Pacaás Novos National Park is a large park conserving mountainous and lowland rainforests and is home to two indigenous cultures