AbstractWe have studied the transient expression, inDictyosteliumcells growing on a bacterial food source, of a construct containing the coding region of the firefly luciferase gene inserted downstream of aDictyosteliumactin promoter. The fusion gene is not detectably expressed when DNA is introduced by calcium phosphate precipitation or by electroporation, but it is expressed when introduced using cationic liposomes (lipofectin). Using this latter procedure, we are able to transform cells with a G418 resistance vector and select stable, drug‐resistant transformants at a relatively low, but workable, efficiency. This technique will allow molecular genetics to be applied to the many important nonaxenicDictyosteliumstrain