Protein microarrays offer a robust way of examining the cellular proteome. The use of protein arrays to study cancer will enable better understanding of the molecular events associated with tumor development and progression. The use of antigen and antibody arrays could revolutionize the area of biomarker discovery, deciphering biochemical and signaling pathways and pharmaceutical research. This review will focus on current developments in the area of protein microarrays and their application in the study of cancer.