The successful completion of the Human Genome Project and other sequencing projects opened the door for another quantum jump in science advancement. The most important public sequence databases are doubling in size every 18 months. By revealing the genetic program of many organisms, these efforts endow biologists with the ability to study the basic information of life in toto as an initial step toward a comprehensive understanding of the complexity of entire organisms. We review the area of synthetic biology, defined as the making and use of biosystems founded on the chemical synthesis of the coding DNA (and potentially RNA). The recent developments discussed here introduce a rich source of oligonucleotides to the field: in situ synthesised microarrays, which in fact represent nothing else but matrix nucleic acid synthesisers. With this new way of producing the oligonucleotides used in the making of synthetic genes in a very cost-effective manner, the field of synthetic biology can be expected to change dramatically in the next decade. Synthetic genes will then be the tools of choice to obtain any sequence at any time in any laboratory.