The reverse transcriptase polymerase chain reaction (PCR) is a technique for the study of gene expression that requires far less RNA for analysis than Northern blots. The inclusion of cRNA standards in the initial reverse transcription step is a way to control for the tube-to-tube variation often inherent in the technique and to permit quantitation of the starting amount of the native mRNA being analyzed. We describe a method using overlapping oligonucleotides to produce templates for the production of cRNA standards for up to three different mRNA species. The first step is the synthesis of a pair of overlapping oligonucleotides each of which encodes, respectively, sequences analogous to either sense or antisense primers for the PCR amplification of up to three different messages. These oligonucleotides are designed to have complementary 3' ends which permit spontaneous annealing and allow subsequent mutually priming extension of the annealed double-stranded portion by T7 DNA polymerase. The T7 and SP6 RNA polymerase promoters are then added to the ends of the template using standard PCR techniques. Once the template is assembled, T7 and SP6 RNA polymerases are used to produce copious quantities of cRNA standards and controls. This technique can be used to construct multiple cRNA standards for essentially any messages of interest. Production of cRNA by a single T7 RNA polymerase reaction yields standards sufficient for several thousand separate reverse transcriptions.