In a current source circuit, a first and a second PNP transistor have commoned base electrodes, their emitters being connected through resistors to the positive supply voltage terminal. The collector lead of the first transistor includes a current source, which supplies a current which is reproduced at the output terminal. The commoned base electrodes are driven by a third transistor connected as an emitter follower, its emitter lead including a current source. The base of the third transistor is connected through a resistor to the positive supply voltage terminal as a result of which supply voltage variations appear also at the commoned bases of the first and second transistors so that the output current at the output terminal is substantially independent of supply voltage variations. A differential amplifier comprising fourth and fifth transistors, in which the base of the fourth transistor is connected to the collector of the first transistor and the base of the fifth transistor is connected to a reference voltage, controls the voltage at the base of the third transistor so that the collector current of the first transistor is substantially equal to the current of the current source.