Experimental infections with Coxiella burnetii augment rates of ribonucleic acid (RNA) synthesis in guinea pigs. The activity of deoxyribonucleic acid-dependent RNA polymerase in L cells persistently infected with C. burnetii was threefold greater than that in unifected cells; the polymerase activity in infected cells was predominantly of class I, whereas that in uninfected cells was predominantly of class II. A search for regulatory factors of polymerase activity revealed that preincubation of uninfected L cells with lipopolysaccharide of C. burnetii or with putrescine, spermidine, or spermine enhanced polymerase activities. Because sonicated nuclei were assayed rather than purified enzymes, it cannot be stated definitely whether augmented polymerase activites were consequences of direct effects of infection on polymerases or a triggering of secondary regulatory factors.