This working paper deals with the individual criminal accountability of employees of private security and/or military companies (PSMCs) in armed conflict. From the perspective of international humanitarian law the PSMCs are interesting because they cause theoretical and practical problems to the current legal system. The private character of these companies does not fit in with the presumed public nature of the national armed forces participating in an armed conflict. The difficulties caused by the PSMCs, however, should not be exaggerated. There is plenty of applicable law both within the international humanitarian legal field and in other sub-systems of international as well as domestic law of states. The problems are primarily practical, they turn on the implementation of the current international legislation which falters for different reasons with respect to the “private warriors”. For the time being, the legal system can remain intact and the “private warriors” can be dealt with as if they were either public warriors - i.e. combatants - or civilians. From the normative point of view it is important that there are no holes in the law that would allow the PSMCs to carry out criminal acts without sanction.