Yellow-fleshed sweetpotato cultivars were included in a series of trials conducted at the Isabela and the Fortuna Agricultural Substations from 1966-67 to 1972-73. At Isabela the soil is a Coto clay (Oxisol) and at Fortuna it is a San Antón silty clay (Mollisol). The cultivars were obtaine.d from introductions,. hybridization, and local collections. The experimental plots generally consisted of four rows 5.45.m (18.0 ft) long and 1.07 m (3.5 ft) apart. Cultivars Gem and R 59-36 yielded better at Isabela than at Fortuna. Cultivar L 963-3 was a heavy yielder at both locations. In general, Cobre yielded better at Isabela than at Fortuna. At Isabela Gem yielded 34.4, 34.1, 36.6, 36.2 and 37.3 tons/ha during 1966-67, 1967-68, 1970-71, 1971-72 and 1972-73, respectively. Gem is a consistently high yielder; however, better yields (45.4 tons/ha) were obtained during 1971-72 at Fortuna. Cobre's best yield (32.7 tons/ha) was obtained at Fortuna in 1971-72. Cultivar L 963-3 yielded 29.4, 30.4, 37.9, and 24.9 tons/ha during 1967-68, 1970-71, 1971-72, and 1972-73, respectively, at Isabela. The best yields from cultivar R 59-36 (36.2 tons/ha) were obtained at Isabela during 1971-72. Cultivars Gem, Cobre, and R 59-36 produced a sizable proportion of roots suitable for canning. A panel of experts concluded that cultivars Gem, Cobre, and R 59-36 peeled easily in a 10% NaOH solution at 214° to 216° F, that boiled sweetpotatoes were of acceptable quality, and that appearance and quality of the canned product was acceptable. Cultivar L 963-3 is more suitable for the fresh market than for canning. Gem had a high carotene content (13.20 mg/100 g).