Abstract
A simple feeding technique for serial passage of typhus rickettsiae in human body lice is descr. Consecutive louse passages are not interrupted by a growth of the rickettsiae in other host species. Applications of the method to passages of epidemic and murine strains are reported. No changes in properties of the rickettsiae were noted during these passages. Multiplication of murine typhus rickettsiae in lice nourished only on human serum is reported.