Environmental conditions can have a dramatic influence on the chemical composition of burley tobacco during the air-curing process. Compositional changes which occur during curing have not been well defined. Therefore, a study was undertaken to determine the influence of temperature and relative humidity on the composition of air-cured burley tobacco. Tobacco was cured at three temperatures; 15, 24 and 32.degree.C at a constant dry rate and at 70, 80 and 90% RH at 27.degree.C. Data will be presented which shows that elevated temperatures accelerate metabolism of the plant pigments, enhances respiration losses and alkaloid losses, and decreases nitrogen losses, while having a synergistic and antagonistic influence on formation of the steam volatile aromatic compounds in the cured leaf. These data will be discussed with respect to the production of a quality burley tobacco.