Molecular biological research into wood development and formation has been the focus in recent years,but the pace of discovery of related genes and their functions in the control of wood properties has been slow. The microarray technique—with its advantages of high throughput capacity, sensitivity, and reliability over other tools developed for investigating genes expression patterns—is capable of rapidly assaying thousands of genes.In this study, a cDNA microarray prepared from two cDNA libraries of developing poplar xylem tissues was used to assay gene expression patterns in immature xylem tissues at different heights from the main stem of Populus deltoides(15 years old), which was confirmed to have distinct wood properties(microfibrillar angle, woody density) by X-ray. Two hundred seventy-four transcripts with differential expression profiles between the chips were screened out, and the individual clones were subjected to 5’ sequencing. Using bioinformatic analysis, we identifiedcandidate genes that may influence poplar wood properties,many of which belong to various regulatory and signal transduction gene families, such as zinc finger protein transcription factor, DNA-binding transcription factor,ethylene response factors, and so on. The results suggest that these genes may regulate enzymes involved in wood formation. Further work will be performed to clone these genes and determine how they influence poplar wood properties. Molecular biological research into wood development and formation has been the focus in recent years, but the pace of discovery of related genes and their functions in the control of wood properties has been slow. The microarray technique-with its advantages of high throughput capacity, sensitivity , and reliability over other tools developed for investigating genes expression patterns-is capable of rapidly assaying thousands of genes. In this study, a cDNA microarray prepared from two cDNA libraries of developing poplar xylem tissues was used to assay gene expression patterns in immature xylem tissues at different heights from the main stem of Populus deltoides (15 years old), which was confirmed to have distinct wood properties (microfibrillar angle, woody density) by X-ray. Two hundred seventy-four transcripts with differential expression profiles between the chips were screened out, and the individual clones were subjected to 5 ’sequencing. Using bioinformatic analysis, we identifie dcandidate genes that may influence poplar wood properties, many of which belong to various regulatory and signal transduction gene families, such as zinc finger protein transcription factor, DNA-binding transcription factor, ethylene response factors, and so on. The results suggest that these genes may regulate enzymes involved in wood formation. Further work will be performed to clone these genes and determine how they influence poplar wood properties.