Abstract: The invention concerns a process for producing middle distillates from effluents obtained from the Fischer-Tropsch process, comprising separating a heavy cut with an initial boiling point of 120-200° C., hydrotreating said cut and fractionating the hydrotreated cut to obtain at least one intermediate fraction and at least one fraction that is heavier than the intermediate fraction. The intermediate fraction boils between T1 and T2, T1 being in the range 120-200° C. and T2 being in the range 300-410° C. The heavy and intermediate fractions are treated over a hydrocracking/hydroisomerisation catalyst and the effluents obtained are distilled. The invention also concerns a unit.