A comparative study, luminescence behavior of 6-Mercaptopurine (6-MP), Azathiopurine (BAN), and 8-Azaguanine (8-Azan) have been investigated including the low temperature phosphorescence, the low temperature fluorescence, the room temperature phosphorescence (RTP) and the room temperature fluorescence (RTF). The effect of pH on the luminescence intensity is discussed. Analytical characteristics of RTF and RTP of 6-MP, BAN, and 8-Azan have been studied. The lifetime of phosphorescence and the polarity of RTF and RTP have been examined.