Puerto de Mejillones is a province in the western parts of the Bolivian department of Oruro.

It is surrounded by Sabaya Province in the north, west and east, and it borders the Republic of Chile in the southwest.

Main language of the province is Spanish, spoken by 97.0%, while 66.6% of the population speak Aymara and 8.6% Quechua (1992).

74% of the population have no access to electricity, 73% have no sanitary facilities (1992).

83.8% of the population are employed in agriculture, 1.0% in industry, 15.2% in general services (2001).