In this study, we investigated gene expression patterns induced by Ailanthus altissima extract and compared it with Gleevec, a well-known anti-leukemia drug, in K562 chromic leukemia cells. Ailanthus altissima extract(100 ug/ml) and Gleevec(50 ug/ml) were treated to cells for 1h, 2h, 4h, and 16h and total RNA was extracted. Gene expressions were evaluated using cDMA microarray, in which 24,000 genes were spotted. Hierarchical clustering analysis showed that expression of genes included in two clusters were increased or decreased time dependently by both Ailanthus altissima extract and Gleevec. Genes included in another cluster were induced by Ailanthus altissima extract but not by Gleevec. In biological process analysis, expression of genes involved in apoptosis, growth arrest and DNA-damage were increased, but genes stimulating cell cycle were decreased. This study provides comprehensive comparison of the patterns of gene expression changes induced by Ailanthus altissima extract and Gleevec in K-562 leukemia cells.