Abstract: A diesel fuel filter comprising an outer casing (2) which is provided at leas with an inlet conduit (40) for the diesel fuel to be filtered (A) and an outlet conduit (41) for the filtered diesel fuel (B), and houses internally at least one first filtering baffle (70) of high filtering efficiency which separates the interior of said casing (2) into two separate chambers, of which a first chamber (8) communicates with the outlet conduit (41) and a second chamber (9) communicates with the inlet conduit (40); the filter (1) also comprises a third chamber (10), which is separated from said first chamber (8) by at least one second filtering baffle (71) permeable to thickened paraffins, and is separated from said second chamber (9) by means (78) arranged to connect said second chamber (9) to said third chamber (10) when the temperature of the diesel fuel to be filtered (A) falls below a value responsible for the formation of thickened paraffins.