By extension the dog latin phrases In vivo - within the living In vitro - in glass (Petri dish, test tube, etc) we now have In silico - in computer. In silico computer based techniques (such as data analysis, correlation studies, etc.) are increasingly important to biologists. Mycoplasma happily live on microbiology media used to grow cell cultures. After all they have been designed to provide an ideal environment in which microbes can grow. Mycoplasma are tiny almost transparent and so hard to detect, but once an experiment has been contaminated with Mycoplasma its results may be useless. The problem of contamination is widespread and has been increasingly recognised. Microbiologists now well understand the problem of bacterial contamination in microbiology labs. Many labs routinely sterilise all their glassware, whether Mycoplasma have been found in the lab or not. However the corresponding problem of computer database corruption has received less attention. Prominent Laboratories exchange microbiology samples. This takes place globally at jet aircraft speed. There are many global biology and bio-medicine databases. They are all linked via the Internet and routinely exchange updates. Such "in silico" exchanges take place at the speed of light. Thus contaminated data may be uploaded in Japan to the Japanese data bank. Then be automatically copied from DDBJ to Washington and from NCBI distributed across the planet. Although Biolgists sterilise their wet labs, they may not even think to clean the data in their computers.