Several techniques are available that detect variations in gene expression between cellular populations. These include subtractive hybridization (SH), differential colony hybridization (DCH) and mRNA differential display, all based on the analysis of mRNA. The first two techniques, however, are limited because they require large amounts of mRNA for SH or several rounds of screening for DCH. Differential display overcomes both of these limitations. However, the conventional differential display technique is plagued by false positives and is labor intensive. The identification of genes that are truly differentially expressed, therefore, becomes a formidable task. We describe a modified differential display technique that overcomes the limitations of the conventional technique. This new technique eliminates a source of false positives, decreases the time required to screen a set of primers and reduces the use of radioactivity.