Field experiment was conducted during kharif seasons of 2003 and 2004 at College farm, College of Agriculture, Rajendranagar, Hyderabad to study the phenology and, heat and radiation use efficiency in aerobic rice. Crop was sown on four different dates viz., 16 June, 26 June, 07 July and 18 July as main plots and two varieties viz., Jagtiala Sannalu and Polasa Prabha as sub-plots in split plot design and replicated thrice. Results revealed that, from emergence to physiological maturity, Jagtiala Sannalu has accumulated mean growing degree days of 2017+55 and heliothermal units of 11526+817 with coefficient of variation of 3% and 7%, respectively. While Polasa Prabha has accumulated 2102+33 mean growing degree days and 12031+716 heliothermal units from emergence to physiological maturity with coefficient of variation of 2 % and 6%, respectively. In both the cultivars i.e.,Jagtila Sannalu and Polasa Prabha higher heat use efficiency (6.61 and 6.29), heliothermal use efficiency (1.30and 1.19) and radiation use efficiency (6.28 and 5.88) were obtained in crop sown on 16 June. In Jagtila Sannalu and Polasa Prabha, physiological maturity can be predicted using AGDD HTU which accounted for 84% and 86% varibility