Microarrays began to be used to study gene expression profiles in the mid-1990s, but it was only after 2000 that serious attempts have been made to apply this technology to investigate sarcomas. Microarray technologies provide a comprehensive survey of active molecular pathways and potential molecular targets for diagnosis and treatment, but are challenging to use because of issues of specimen collection, cost, and complexities in experimental design and data analysis. As a discovery-based technique, microarray analyses are most valuable when framed around specific gaps in our knowledge of tumor etiology and progression, challenges in differential diagnosis, and pressing therapeutic needs. To date, microarray analyses of sarcomas support their division into molecularly defined and molecularly heterogeneous categories, and have provided useful diagnostic markers for entities such as gastrointestinal stromal tumors, synovial sarcoma, and dermatofibrosarcoma protuberans. Signatures predicting outcome and response to therapy have been published for Ewing sarcoma and osteosarcoma, and receptor tyrosine kinase expression patterns have suggested novel therapeutic approaches which may be applied to several types of sarcoma. Nevertheless, results need to be interpreted in the context of histopathology and validated by complementary technologies and/or other research groups.