Background: Male breast cancer (MBC) is a rare disease and little is known about its etiopathogenesis. Array comparative genomic hybridization (aCGH) provides a method to quantitatively measure the changes of DNA copy number and to map them directly onto the complete linear genome sequences. The aim of this study was to investigate DNA imbalances by aCGH and compare them with a female breast cancer dataset.Methods: We used Agilent Human Genome CGH Microarray Kit 44B and 44K to compare genomic alterations in 25 male breast cancer tissues studied at NCC of Bari and 16 female breast cancer deposited with the Gene Expression Omnibus (GSE12659). Data analysis was performed with Nexus Copy Number 5.0 software.Results: All the 25 male and 16 female breast cancer samples displayed some chromosomal instability (110.93 alterations per patient in female, 69 in male). However, male samples presented a lower frequency of genetic alterations both in terms of loss and gains.Conclusion: aCGH is an effective tool for analysis of cytogenetic aberrations in MBC, which involves different biological processes than female. Male most significant altered regions contained genes involved in cell communication, cell division and immunological response, while female cell–cell junction maintenance, regulation of transcription and neuron development.