We report on fabrication and characterization of polymer light emitting diode by using a thin film of pure deoxyribonucleic acid as electron blocking layer (EBL). A thin film of phosphorescent Ir(ppy)(3) luminophore, embedded in the poly(N-vinylcarbazole) (PVK)/2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD) is used as emission layer. The obtained BioLED shows a good stability and its luminous efficiency is improved by ca 40% as compared to the case without EBL. The result shows that using the DNA layer one can either improve the OLED brightness at the same current density or operate at a significantly lower current density with the same brightness than without it.