We have established a genetic quality testing system for early stage embryos of the mouse. A method of preparation of template DNA for PCR was established using the lysis buffer (1 x PCR reaction buffer supplemented with proteinase K at a concentration of 40 microg/ml) developed by the authors. We demonstrated that two 8-cell embryos of an inbred strain provide sufficient volumes of template DNA for PCR to identify the strain of embryos using four microsatellite markers (D3Mit54, D5Mit18, D6Mit15 and D8Mit50) differentiating 13 inbred strains of mice. This system will be useful in embryo banks that have recently been established worldwide for demonstrating the genetic accuracy of a given strain prior to recovery of live animals.