A process for the refining of crude tall oil, wherein the process comprises fractionation under vacuum of a refined CTO into at least one stream of refined tall diesel, said RTD comprising from 2 - 40 % by volume of resin acids and from 20 - 90 % by volume of fatty acids, characterized by a pre-treatment step involving CTO washing and separation of impurities, from which pre-treatment step a first refined CTO stream is obtained, said first refined CTO stream then being further processed in a steam stripper or a thin-film evaporator to remove volatile components forming and yield a second refined and substantially volatiles free CTO stream which is further processed in fractionation under vacuum, wherein the fractionation under vacuum is performed in at least three steps in at least three units: 1) the refined and substantially volatile free CTO is charged to a first fractionation step for separation of tall oil pitch from RTD components and resin acids present in the refined CTO, wherein the first fractionation step is performed in one or more thin-film evaporators arranged in parallel or series at 250-320°C and at a low pressure of 0.7-1.5 kPa, and the temperature of the TOP and volatile depleted tall oil comprising RTD components and resin acids exiting the TFE is in the range of 200-330°C prior to charge into a fractionation tower equipped with one or more structured packing(s), wherein heat is supplied to the TFE by steam or hot oil; 2) followed by a second fractionation step, of the stream containing RTD components and resin acids obtained in the first fractionation step, in a main vacuum fractionation tower operating under vacuum conditions of 1-25 mbar and at a temperature in the range 150-280°C, wherein a stream rich in RTD components having a boiling point at atmospheric pressure in a range of 170 - 420°C is separated from a stream of RA components having a boiling point above about 420°C at atmospheric pressure; and 3) in a third fractionation step the stream of RA components from the second fractionation step is further refined into RA with a low fatty acid content, wherein the stream of RA components recovered from a lower section of the main fractionation tower in the second fractionation step is discharged into the RA purification step performed in a second fractionation tower, or further processed in a thin-film evaporator for separation of entrained TOP components from RA(s), said RA(s) being further refined by processing under vacuum in the RA purification step performed in a second fractionation tower in order to produce high quality RA(s) comprising less than about 4 wt% fatty acids; so that the fractionation also yields at least one stream of resin acid(s) comprising less than 5 % by volume of fatty acids, wherein the stream of RTD is deoxygenated forming hydrocarbon compounds in a subsequent step. 1) the refined and substantially volatile free CTO is charged to a first fractionation step for separation of tall oil pitch from RTD components and resin acids present in the refined CTO, wherein the first fractionation step is performed in one or more thin-film evaporators arranged in parallel or series at 250-320°C and at a low pressure of 0.7-1.5 kPa, and the temperature of the TOP and volatile depleted tall oil comprising RTD components and resin acids exiting the TFE is in the range of 200-330°C prior to charge into a fractionation tower equipped with one or more structured packing(s), wherein heat is supplied to the TFE by steam or hot oil; 2) followed by a second fractionation step, of the stream containing RTD components and resin acids obtained in the first fractionation step, in a main vacuum fractionation tower operating under vacuum conditions of 1-25 mbar and at a temperature in the range 150-280°C, wherein a stream rich in RTD components having a boiling point at atmospheric pressure in a range of 170 - 420°C is separated from a stream of RA components having a boiling point above about 420°C at atmospheric pressure; and 3) in a third fractionation step the stream of RA components from the second fractionation step is further refined into RA with a low fatty acid content, wherein the stream of RA components recovered from a lower section of the main fractionation tower in the second fractionation step is discharged into the RA purification step performed in a second fractionation tower, or further processed in a thin-film evaporator for separation of entrained TOP components from RA(s), said RA(s) being further refined by processing under vacuum in the RA purification step performed in a second fractionation tower in order to produce high quality RA(s) comprising less than about 4 wt% fatty acids;