Heterologous expression of recombinant proteins in yeast involves toilsome screening of a large number of recombinants from yeast cells. A quick and easy procedure was introduced for identifying recombinant clones from the yeast Saccharomyces cerevisiae by means of PCR without any prior DNA extraction and purification steps. This method involves a simple boiling step for 2～5 min of whole yeast cells suspended in water. Both the fresh and frozen competent S.cerevisiae cells can be used for transformation. The method of storing the competent yeast cells at －80℃ for future use is convenient and economic. A skill of decreasing the dimer products and increasing the specificity of PCR is recommended.