In vitro dose-response relationships are used to describe the relation between dicentric chromosomes and radiation dose for human peripheral blood lymphocytes. The dicentric yield depends on both the dose and the radiation quality. Thus, for reliable dose estimation in vitro dose responses must be determined for different radiation qualities. This paper reports the work for setting up the relationship for the dicentric production in the lymphocytes exposed in vitro to 192Ir g-rays at Central Laboratory for Radiological Protection (CLOR). In a case of a radiation accident in industrial radiography using 192Ir sealed sources, this will be the basis for the indirect evaluation of the g-ray dose to which an accidental victim was exposed.