In this paper we investigate the amplified spontaneous emission (ASE) phenomenon in the system based on a dye dissolved in a modified deoxyribonucleic acid (DNA). The system consisted of a biopolymeric matrix made of DNA blended with cationic surfactant molecule cetyltrimethyl-ammonium chloride (CTMA) and doped with a well-known rhodamine (Rh 6G) laser dye. Thin films of the DNA–CTMA : Rh6G were excited at λ = 532 nm wavelength with 8 ns laser pulses. We report on ASE intensity as a function of the laser power, dependence of polarization state of the excitation beam, ASE gain and temporal stability of the signal for the investigated system.