Experiments that deal with the stability of messenger RNA (mRNA) in normal mouse kidney, and, to some extent, the stability of mRNA during renal growth will be described. We have found a population of mRNA in the cytoplasm of mouse kidney that is short-lived. Such a class of rapidly metabolized mRNA could play an adaptive role at the translational or cytoplasmic level in determining gene expression and may be important during the early phases of compensatory hypertrophy.