Mutations in the WT1 gene are found in a subset of Wilms' tumours and in certain other disorders such as Denys-Drash syndrome. The WT1 gene product is a zinc finger transcription factor for which many target genes have been suggested. Here we utilise gene targeting to generate cells containing only truncated forms of WT1, in which the DNA-binding region is disrupted. Examination of gene expression in these cells using cDNA macroarrays suggests two novel WT1 transcriptional targets, cyclin G1 (Ccng1), and insulinlike growth factor binding protein 4 (Igfbp4).