['Cholangiocarcinoma (CC) is a rare tumour with a dismal prognosis. As conventional medical management offers minimal survival benefit, surgery currently represents the only chance of cure. We evaluated DNA copy number (CN) alterations in CC to identify novel therapeutic targets.', 'DNA was extracted from 32 CC samples. Bacterial artificial chromosome (BAC) array comparative genomic hybridization was performed using microarray slides containing 3400 BAC clones covering the whole human genome at distances of 1 Mb. Data were analysed within the R statistical environment.', 'DNA CN gains (89 regions) occurred more frequently than DNA CN losses (55 regions). Six regions of gain were identified in all cases on chromosomes 16, 17, 19 and 22. Twenty regions were frequently gained on chromosomes 1, 5, 7, 9, 11, 12, 16, 17, 19, 20 and 21. The BAC clones covering ERBB2, MEK2 and PDGFB genes were gained in all cases. Regions covering MTOR, VEGFR 3, PDGFA, RAF1, VEGFA and EGFR genes were frequently gained.'] Does array comparative genomic hybridization identify novel potential therapeutic targets in cholangiocarcinoma?