This article sheds new light on the history of Afro-Yungueño Spanish (AY), an isolated variety of Spanish spoken by descendants of slaves in the Bolivian Yungas valleys, and examines the possibility of a Portuguese input to it. First, new ethnographic and historical data are introduced to show that the AY speakers in Mururata, Chijchipa, and Tocaña probably descend from African slaves who arrived in Bolivia during the 18th century from different parts of the Portuguese slave trade area. As this suggests that Portuguese may have been involved in the history of AY, the second part of this paper, after describing some of its particularities, compares AY with Africanized varieties of Portuguese, above all Afro-Brazilian Portuguese, to show that there is evidence to assume that AY is related to certain varieties of Afro-Portuguese. The final discussion considers the contributions of AY to the debates on Afro-Iberian speech varieties.