Two histochemical marker genes, Drosophila alcohol dehydrogenase (ADH) and human placental alkaline phosphatase (ALP), were cloned into the recombinant retroviral vectors pLJ and pgag beta-actin. The resulting vectors were transfected into retroviral producer cell lines, psi CRE and psi CRIP, and stable recombinant retrovirus producers were isolated. Recombinant virus was harvested and used to transduce genes into several cell lines, singly or in conjunction with lacZ (Escherichia coli beta-galactosidase)-containing retrovirus. Cell lines were then stained using standard histochemical methods for recombinant gene expression. We found that multiple gene products could be identified in the same cell populations and in the case of ALP and beta-galactosidase, in the same cells. The resulting reagents should be useful for a variety of cell-marking studies including those involving multiple clonal analysis and developmental studies for gene therapy.