In 2000, cassava production in Puerto Rico was almost 750,000 kg with an annual farm value of $386,000. During the same year more than 6,800,000 kg of cassava tubers were imported. Studies with new introductions of cassava clones are necessary to increase production, reduce costs and meet local demand. Seven cassava introductions and one local cultivar were evaluated in 1997 and 1998 at Corozal for yield and hydrogen cyanide (HCN) concentration. Clones CM 3380, CM 3311, SG 804 and SM 494 produced the highest number of marketable roots. Clones CM 3311, CM 3380 and SG 804 produced the highest root marketable weight in 1997, averaging 37,905 kg/ ha. In 1998, clones CM 3311 and CM 3380 were the best yielders, averaging 28,713 kg/ha of marketable roots. In both years clone SG 804 had a significantly higher concentration of HCN, which averaged 121 mg/kg, whereas the rest of the clones had values of HCN below 63 mg/kg.