Dear Editor:rnWe would like to show “changes in intestinal lengths of 129S2/SvPasCrl mice from adulthood to agedness”.The intestine functions not only in digestion, absorption and excretion, but also in the regulation of central nervous system through its microbiota so as called gut-brain axis[1].As a tubular organ, the intestinal length is regarded as a significant morphological characteristic, which directly affects digestion and absorption[2].Thus, clarifying changes in intestinal lengths at different ages is beneficial to understand the functions of the digestive system as well as the aging process.