An experimental model with accelerated but not drastic renal senescence seemed useful to recognize the mechanisms of how kidney function deteriorates with age. Senescence marker protein-30 (SMP30), whose expression decreased with age and was sex-independent, is mainly expressed in hepatocytes and proximal tubular cells. Therefore, we established a SMP30 deficient strain of mice with a C57BL/6 background by gene targeting to investigate whether this molecule is involved in renal tubular cell senescence. Male SMP30 knockout (SMP30Y/-) mice and male wild-type (SMPY/+) mice (n=5) aged 12 months were examined histologically. Their tubular epithelia showed the deposition of lipofuscin and the presence of senescence-associated beta-galactosidase (SA-beta-GAL). However, no tubular cells were atrophic. In electron microscopy, SMP30-KO mice showed markedly enlarged lysosomes containing an electron dense substance. These are convincing hallmarks of senescence. We recognized the early manifestation of senescence hallmarks in SMP30-KO mice at 12 months old. Thus, this model represents the first report of a mouse strain that manifests accelerated ordinal senescence in a kidney after gene manipulation.