The factors explaining the evolution of part-time job are essentially two: the need for more flexibility and the influence of the European Community legislation on national labour law. In the essay the most recent amendments to the Italian legislation are taken into consideration - in the light of the Ec law - to check the consequences of labour time flexibility, which is mainly orientated towards production requirements. The weakest point of today's part-time discipline is the scarce possibility for the worker to take advantage of the multiple hypotheses the legislation allows in changing the number of working hours and timeframe. The "job on call", introduced by the most recent reform, is representative of this trend to enable a flexibility, which is beneficial to the employer only.