An Implantable delivery device comprising at least a body (1), an inlet (2 17 46) and an outlet (3 18 47) and actuating means, wherein the actuating means comprise at least an actuator displacing a piston (6 21 32) in a rotating cylinder (4 19 31) forming at least one variable volume chamber (8,8' 22,22' 53), the volume of which is varied by rotation of said cylinder thereby pumping liquid such as a drug from a reservoir through said inlet (2 17 46) and expelling said pumped liquid from said variable volume chamber through at least a first temporary chamber (9, 10 23,24 40, 41) and said outlet (3 18 47) by variation of said volume.