1. This study extends previous work concerned with the ribonucleic acid made by Escherichia coli during inhibition of protein synthesis by chlortetracycline. 2. The antibiotic caused an initial stimulation in the rate of RNA synthesis. 3. RNA made during inhibition was stable during continued incubation in the presence of the antibiotic although it was extensively degraded in resting cell suspensions. 4. Most of the RNA accumulated during chlortetracycline action was in particles that sedimented more slowly than ribosomes. During the recovery of cells from the effects of the antibiotic, accumulated RNA was apparently not degraded and ribosomes were synthesized from the RNA in the particles.