This study reports the impact of one step annealing on the composition, molecular structure, granule morphology and physicochemical properties of starches isolated from cultivars of Dioscorea esculenta (kukulala, java-ala-nattala) and Dioscorea alata (hingurala, raja-ala), yam tubers grown in Sri Lanka. In all starches, granule morphology (shape, size, surface appearance), birefringence patterns, acid hydrolysis profile and X-ray patterns remained unchanged on annealing. Crystallinity remained unchanged on annealing in hingurala, kukulala and java-ala. However, crystallinity of raja-ala and nattala increased and decreased, respectively, on annealing. In all starches, annealing decreased the gelatinization temperature range (kukulala ∼ hingurala > nattala ∼ raja-ala > java-ala), amylose leaching (raja-ala > nattala > hingurala > kukulala > java-ala), granular swelling (raja-ala ∼ hingurala > kukulala > java-ala > nattala), peak viscosity (raja-ala > hingurala > kukulala > java-ala > nattala), enthalpy of retrogradation (kukulala ∼ java-ala ∼ nattala ∼ hingurala ∼ raja-ala) and susceptibility towards acid hydrolysis (java-ala > raja-ala > hingurala ∼ nattala > kukulala). However, annealing increased gelatinization temperatures (kukulala ∼ java-ala ∼ nattala ∼ raja-ala ∼ hingurala) and the enthalpy of gelatinization (kukulala > hingurala > java-ala > nattala > raja-ala). Set-back viscosity increased in nattala, but decreased in the other starches (raja-ala > hingurala > kukulala > java-ala) on annealing. The study showed that the different responses shown by the cultivars of the Dioscorea starches towards annealing were to a large extent influenced by their composition and molecular structure.