Microdisc array (MDA) electrodes of boron-doped diamond (BDD) were fabricated on structured silicon substrates. The BDD-MDA electrodes exhibited sigmoidal voltammetric curves, which show that they function as assemblies of single microelectrodes. The microelectrode behavior was also confirmed with biologically important species such as ascorbic acid and 3,4-dihydroxyphenyl acetic acid, indicating its applicability in electroanalysis.