Sweet potato is considered a successful competitor against some weeds. Amaranthus dubius is a common weed that adversely affects sweet potato production throughout the Caribbean Basin. Limited research has been performed on weed interference in sweet potato under tropical conditions. In this scenario, understanding weed-crop relationships is fundamental for developing economical weed control strategies. A study was conducted to determine the effect of A. dubius interference on sweet potato mineral uptake under tropical conditions. Treatments included sweet potato without A. dubius, interspecific sweet potato with A. dubius, and A. dubius alone. At 5, 7, 9, 11 and 13 weeks after planting, two plants per plot and per species were cut at the soil level, washed and divided in leaf lamina, petiole and stem for nutrient concentration analyses. Interference by A. dubius significantly reduced sweet potato's uptake of Ν, Κ and Mg at 11 weeks after planting and later. Uptake of Ρ and Ca was reduced at 13 weeks after planting.