Abstract:The common procedure for purification of total messenger RNA (mRNA) from plant leaves, Apium graveoleus L. as material, has been described. The activities of protein synthesis and reverse transcription of the mRNA were determined. The leaves of Apium graveoleus L. different stage of growth contain variable content of the RNA (total RNA and mRNA). The length and distribution of the poly(A) at 3′-end of the mRNA were estimated. The maxium length of poly(A) were determined as 165 ± 5 A-residues.