Expressed sequence tags (ESTs) provide an efficient route to the identification of genes involved in normal development and in disease. PCR amplification of somatic cell hybrid DNAs was used to localise 22 brain-derived ESTs to subregions of human chromosome 11. Problems encountered with the standardised PCR conditions were overcome by optimising the annealing temperatures and the use of "touchdown" PCR. Amplification of the correct target sequence allowed the mapping of 19 ESTs, 8 to the short arm and 11 to the long arm of chromosome 11. No definitive localisation could be determined for the three remaining ESTs.