Rio Guaporé is the name of a river in western Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

 along the Bolivia

Bolivia

Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...

n border. Its Bolivian name is Río Iténez.

The river has its source in the Brazilian Mato Grosso

Mato Grosso

Mato Grosso is one of the states of Brazil, the third largest in area, located in the western part of the country.Neighboring states are Rondônia, Amazonas, Pará, Tocantins, Goiás and Mato Grosso do Sul. It also borders Bolivia to the southwest...

 circa 150 km northeast of Pontes e Lacerda

Pontes e Lacerda

Pontes e Lacerdais a municipality Brazilian state of Mato Grosso. Is located 450 km from Cuiaba, at a latitude 15° 13'34" south and a longitude 59° 20'07" west, with an altitude of 254 meters. Its estimated population in 2006 was 42,429 inhabitants...

. From this town on it flows in a westerly direction for about 120 km, where at Vila Bela da Santíssima Trindade

Vila Bela da Santíssima Trindade

Vila Bela da Santíssima Trindade is a Brazilian municipality in Mato Grosso with 14,523 inhabitants. It is located at upper Guaporé River close to the border with Bolivia...

 it is joined by Rio Alegre

Alegre River (Mato Grosso)

-References:*...

. It flows in a northerly direction for another 180 km and from then on it forms the borderline between the Brazilian states Mato Grosso and Rondônia

Rondônia

Rondônia is a state in Brazil, located in the north-western part of the country. To the west is a short border with the state of Acre, to the north is the state of Amazonas, in the east is Mato Grosso, and in the south is Bolivia. Its capital is Porto Velho. The state was named after Candido Rondon...

 to the northeast, and Bolivia

Bolivia

Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...

n departments Santa Cruz

Santa Cruz Department

Santa Cruz, with an area of 370,621 km², is the largest of the nine constituent departments of Bolivia. In the 2001 census, it reported a population of 2,029,471. The capital is the city of Santa Cruz de la Sierra. The state is one of the wealthiest states in Bolivia with huge reserves of...

 and Beni

Beni Department

Beni, sometimes El Beni, is a northeastern department of Bolivia, in the lowlands region of the country. It is the second largest department in the country , covering 213,564 square kilometers , and it was created by supreme decree on November 18, 1842 during the administration of General José...

 to the southeast. Here it carries the name Iténez on the Bolivian and Guaporé on the Brazilian side, before it joins Río Mamoré at Sorpresa

Sorpresa

¡Sorpresa! TV is an American Spanish-language children's television channel. The channel is currently available on Cablevision, Charter Communications, Comcast, Cox Communications, Time Warner Cable, Verizon FiOS and member systems of the National Cable TV Cooperative...

.