The present invention is directed to compositions and methods useful for the amplification of nucleic acid molecules by reverse transcriptase-polymerase chain reaction (RT-PCR). Specifically, the invention provides compositions and methods for the amplification of nucleic acid molecules in a simplified one- or two-step RT-PCR procedure using combinations of reverse transcriptase and thermostable DNA polymerase enzymes in conjunction with sulfur-containing molecules or acetate-containing molecules (or combinations of such sulfur-containing molecules and acetate-containing molecules), and optionally bovine serum albumin. The invention thus facilitates the rapid and efficient amplification of nucleic acid molecules and the detection and quantitation of RNA molecules. The invention also is useful in the rapid production and amplification of cDNAs which may be used for a variety of industrial, medical and forensic purposes.