A study was conducted in 2010 to evaluate the effect of prolonged yellowing on the quality and chemical composition of flue-cured tobacco (Nicotiana tabacum L.) leaves. Ripe flue-cured tobacco leaves were maintained at a dry bulb temperature of 38 °C and wet bulb temperature of 36 °C for up to 8-32 h after yellowing was basically completed. An uncured control treatment (CK2) which was oven-dried immediately after harvest, a cured treatment (CK1) and two treatments (T1 and T2) were analysed for changes in dry-mass loss and chemical composition. The results showed that the dry-mass declined linearly. Most of the starch was degraded during yellowing and the remainder of the starch continued degrading to over-yellow. The results suggested that over-yellowing for up to 8 h (lower leaf), 12 h (middle leaf), 16 h (upper leaf) improved quality and may be associated with the decline in starch.