Klotho is a membrane protein and hormone mainly expressed in the kidney and counteracting ageing thus leading to increase of life span. Klotho-deficient mice suffer from severe growth deficit, rapid ageing and early death. Conversely, the life span is substantially increased in Klotho overexpressing mice. Another determinant of life span is insulin/IGF1. Excessive insulin/IGF1 activity accelerates ageing. Insulin/IGF1 signaling includes activation of phosphatidylinositide (PI) 3 kinase with subsequent activation of Akt and SGK and Akt/SGK dependent inhibition of GSK3. In the present study Klotho transcript levels were determined by RT-PCR in human embryonic kidney (HEK) cells as well as in kidneys from wild type mice and knockin mice expressing Akt/Sgk resistant GSK3a,b (gsk^ki). In HEK cells, serum deprivation increased Klotho transcript levels, an effect reversed by addition of insulin (100 nM) or IGF1 (100 mg/ml), mimicked by pharmacological inhibition of PI3 Kinase with Wortmannin (250 nM) or LY294002 (20 nM), and paralleled by increase of GSK3 phosphorylation. The effect of LY294002 (20 mM) on Klotho transcript levels in HEK cells was significantly blunted by pharmacological inhibition of GSK3 with LiCl (10–20 mM) or the specific GSK3 inhibitor SB216763 (5–10 mM). Klotho transcript levels were significantly higher in gsk^ki mice than in wild type animals, a difference paralleled by lower plasma levels of 1,25(OH)₂D₃ and higher plasma levels of FGF23. In conclusion, the present observations disclose that insulin/IGF1 downregulate Klotho expression through PI3K/PKB/GSK3 signaling and thus reveal the convergence of two major molecular determinants of ageing.