Abstract: The influence of age on tuber yield, dry matter content, cooking quality and flour, gari and starch yield were studied on 4 cassava accessions (DMA-002, WCH-037, NKZ-009 and NKZ-015) at six selected locations in the Forest and the Transition ecozones of Ghana in 2004/2005. The aim was to determine the effect of age, variety and location on agronomic and processing characteristics of cassava genotypes at the Forest and the Transition ecozones of Ghana. Data were collected for the tuber yield, dry matter content, cooking quality, flour, gari and starch yields. Planting was done at 1x1 m with each genotype occupying half of an acre to facilitate continuous harvesting and for large tuber samples of 25 kg to be processed into flour, gari and starch. Harvesting which began at 12 months after planting was continued monthly until 15 months of age. Tuber yield of the genotypes was generally higher in the Transition than the Forest. In addition, DMA-002 and WCH-037 produced the higher tuber yield than the NKZ-lines in the Transition belt but not in the Forest ecozone. Genotypes did not only vary in dry matter content at the two ecozones but also the age at harvest. Cooking quality of the DMA-002 and WCH-037 was better than the NKZ-lines. Obtained results revealed that the optimum age for root tuber yield did not coincide with that of the flour, gari and starch. Similar observation was made between the starch, flour and gari.