Field experiment was conducted during kharif seasons of 2009 and 2010 at Agricultural Research Institute, A.N.G.R. Agricultural University, Rajendranagar, Hyderabad to study heat and radiation use efficiency of maize crop. The experiment was in four dates of sowing (7 July, 21 July, 6 August and 22 August in 2009 and 18 June, 02 July, 17 July and 02 August in 2010) with recommended dose of fertilizer (200kg ha-1). Results revealed that the mean AGDD, AHTU and APTU were 1740+29, 9025+1477 and 21155+812, respectively from emergence to physiological maturity. Crop took 110+4 calender days from emergence to physiological maturity. Progressive delay in sowing caused a decrease in AGDD i.e., 1754 to 1717 in 2009 and 1788 to 1746 in 2010. Higher heat use efficiency of 8.44 and 8.42kg oC day1 for biomass and 4.93 and 4.68 kg oC day-1 for grain and radiation use efficiency of 7.99 and 8.19 kg MJ1 for biomass and for grain 4.55 and 4.57 kg MJ-1were obtained in crop sown on 21 July in 2009 and 18 June in 2010 respectively.