Abstract: Within the near future it will be possible to survey expression of all genes in a sample by microarray analysis. Current methods for nucleic acid amplification require microgram amounts of complementary DNA or RNA for hybridization to microarrays. Without amplification, such amounts are only obtainable from millions of cells. However, frequently such numbers are not available: aspiration biopsies, rare population subsets isolated by cell sorting or laser capture, or micromanipulated single cells are examples where few or even only single cells containing the desired information may be at hand. The current invention reduces the input amount of RNA needed for microarray analysis by a million-fold, and yields reproducible results from the picogram range of total RNA obtainable from a single cell. Of central importance to the present claims, the invention generates an amplified cDNA product in which the abundance relationships of the original RNA are faithfully preserved throughout amplification.