A novel method for analysing and comparing the relative amounts of the most abundant (higher than 0.1% abundance) individual mRNAs present in different poly(A)+RNA preparations has been developed. This method is based on the synthesis of short (10-30 nucleotide) cDNA termination products, by reverse transcription of poly(A)+RNA primed with a 5'-labeled oligonucleotide. A set of 30 different oligonucleotides are used as primers in separate reactions, their length and sequences having been chosen to provide more than a 90% probability of initiating synthesis from any individual RNA present in the poly(A)+RNA. Each primer produces about 10-60 bands per track, following polyacrylamide gel electrophoresis under denaturing conditions. Data presented reveals poly(A)+RNA pattern differences for a number of human tissues and identifies changes in RNA patterns between normal tissues and neoplastic human tumors (myoma of the uterus) from several individuals.