Antibody microarrays, one emerging class of proteomic technologies, have broad applications in proteome analysis, disease diagnostics and quantitative analysis. Compared to DNA microarrays, protein targets have significantly more complex interactions with their ligands such as antibodies. To introduce antibody microarrays for clinical diagnostics and thus to complement or replace conventional immunoassays, several new developments are addressed. We discuss different microarray surfaces, immobilization techniques, detection systems and advantages and disadvantages of antibody microarrays compared to standard clinical techniques. Currently, the probes with highest specificity, well-characterized binding properties, and the possibility of large-scale production using display libraries are recombinant antibodies.