Stability of RNA was tested in strains of Escherichia coli carrying single, double, or triple mutations in the RNA processing enzymes RNase III, RNase E and RNase P. Tests were carried out for total pulse labeled RNA, beta-galactosidase mRNA and for the decay of preexisting RNA during carbon starvation. Decay of RNA was measured at permissive and nonpermissive temperatures, and in no case were significant differences between mutants and non-mutant strains found. Therefore, we conclude that the three processing enzymes; RNase III, E and P do not contribute significantly to turnover of RNA IN Escherichia coli.