An extended release oral dosage form comprising as active substance tacrolimus or a pharmaceutically active analogue thereof for a once daily immunosuppressive treatment of a patient in need thereof, preferable a kidney or liver transplant patient. The dosage form releases the active substance over an extended period of time. It also provides improved pharmacokinetic parameters due to an extended and constant in vivo release including substantial decreased peak concentrations, despite increased bioavailability, substantial extended times for maximal concentration, and higher minimal concentrations when compared with conventional immediate release dosage forms and a recent modified release tacrolimus dosage form.