The (one-step) method has become widely used to isolate total RNA from living organism samples and from different tissues. The aim of this study is to extract RNA from the blood and testicular tissue of male local chickens. The principle behind the method is to separate the RNA from the DNA after extraction with an acid solution containing (Acid guanidinium thiocyanate-phenol-chloroform) with centrifugation, under acidic conditions, the total RNA remains in the upper aqueous phase while most of the acid descends. The DNA and proteins are either in the interphase or in the lower organic phase and then the total RNA is collected by precipitation with isopropanol. Our results showed a significant increase in the concentration of RNA extracted from the blood compared to the testis tissue of local roosters. This protocol made it possible to isolate RNA from cells and tissues in less than 4 hours and was the reason for the great advances in gene expression analysis in plant and animal models, as well as in pathological samples as clearly demonstrated by the huge number of citations the protocol has gained in the past 20 years.