Bacterial contamination is a serious problem in plant tissue culture. In in vitro cultures, if bacteria are introduced, it is most frequently with the initial explants, but bacterial contamination can also come from the laboratory environment or from the staff themselves. Exogenous bacteria are easier to deal with, but endogenous bacteria remain problematic. Standard sterilization with ethanol, NaOCl or HgCl2 and with antibiotics can now be enriched with new components (NaDCC, AgNO3, nano-silver) or sanitation products (PPMTM, ProClin? 300, Biosept 33 SL, Vitrofural?, Dekaben). Some of these can be incorporated into a multiplication and rooting medium for one or more passages, if they are not phytotoxic to the plant explants. A special problem is presented by cryptic or viable but not cultivable bacteria which can be unable to multiply during many passages, but finally be disclosed in mass. The issue is, therefore, to find and apply tools for detection of different media and/or molecular markers. The above questions are discussed in the present paper based on the literature and results of our own study.