to the present invention is similar to an ordinary procedure except for the use of a reaction solution whose ph is higher than that employed usually and or the addition of a polyamine and or a sulfated polysaccharide thus in an rt reaction the reaction is proceeded for about 30 minutes to 1 hour at a temperature suitable for a primer and a reverse transcriptase selected in a pcr a dna is first converted into a single stranded dna by means of a thermal denaturation denaturation step secondly the primers between which a region to be amplified is sandwiched are hybridized annealing step subsequently the primers are elongated by a dna polymerase in the presence of 4 deoxyribonucleotides datp dgtp dctp dttp polymerization step the present invention is further described in the following examples which are not intended to restrict the invention in this experiment a human blood was added directly to a reaction solution established in the present invention to perform an rt pcr using a primer specific to a human beta actin mrna in the rt pcr 1 u03bcl of the human blood was added to 50 u03bcl of the reaction solution the primer for the rt reaction was an oligonucleotide bar having the sequence complementary to the human beta actin mrna and then in the subsequent pcr an oligonucleotide baf having the.