A method for the assessment of the contamination of a rail, in particular for a railway vehicle, comprising the steps of: - imposing a first sliding value (δ 1) lower than a first predetermined threshold (t 1) between the wheels (W 1) of a first controlled axle (A 1) of a rail vehicle and the rail, the first controlled axle (A 1) being the head axle of the railway vehicle according to the direction of travel of the railway vehicle; - imposing a second sliding value (δ 2) greater than a second predetermined threshold (t 2) between the wheels of a second controlled axle (A 2) and the rail, the second axle (A 2) being the axle following said first axle (A 1) according to the direction of travel of the train, and the second predetermined threshold (t 2) being greater than said first predetermined threshold (ti); - determining the trend of the adhesion curve between the wheels belonging to a plurality of controlled axles (A n) of the railway vehicle and the rail, based on a first adhesion value (μ 1) between the wheels of said first axle (A 1) and the rail, and a second adhesion value (μ 2) between the wheels of said second axle (A 2) and the rail; wherein said step of determining the trend of the adhesion curve between the wheels belonging to a plurality of controlled axles (A n) of a railway vehicle and the rail comprises the steps of: - measuring the first adhesion value (μ 1) between the wheels of said first axle (A 1) and the rail, and the second adhesion value (μ 2) between the wheels of said second axle (A 2) and the rail; - if the second adhesion value (μ 2) is greater than the first adhesion value (μ 1), determining that the adhesion curve between the wheels belonging to the plurality of controlled axles (A n) of a railway vehicle and the rail is an adhesion curve having a trend which has an adhesion peak (μ p) at a sliding value (δ p) greater than the second predetermined threshold (t 2); and - if the second adhesion value (μ 2) is lower than the first adhesion value (μ 1), determining that the adhesion curve between the wheels belonging to a plurality of controlled axles (A n) of a railway vehicle and the rail is an adhesion curve having a trend which has an adhesion peak (μ p) at a sliding value (δ p) lower than said first predetermined threshold (t 1). - imposing a first sliding value (δ 1) lower than a first predetermined threshold (t 1) between the wheels (W 1) of a first controlled axle (A 1) of a rail vehicle and the rail, the first controlled axle (A 1) being the head axle of the railway vehicle according to the direction of travel of the railway vehicle; - imposing a second sliding value (δ 2) greater than a second predetermined threshold (t 2) between the wheels of a second controlled axle (A 2) and the rail, the second axle (A 2) being the axle following said first axle (A 1) according to the direction of travel of the train, and the second predetermined threshold (t 2) being greater than said first predetermined threshold (ti); - determining the trend of the adhesion curve between the wheels belonging to a plurality of controlled axles (A n) of the railway vehicle and the rail, based on a first adhesion value (μ 1) between the wheels of said first axle (A 1) and the rail, and a second adhesion value (μ 2) between the wheels of said second axle (A 2) and the rail; - measuring the first adhesion value (μ 1) between the wheels of said first axle (A 1) and the rail, and the second adhesion value (μ 2) between the wheels of said second axle (A 2) and the rail; - if the second adhesion value (μ 2) is greater than the first adhesion value (μ 1), determining that the adhesion curve between the wheels belonging to the plurality of controlled axles (A n) of a railway vehicle and the rail is an adhesion curve having a trend which has an adhesion peak (μ p) at a sliding value (δ p) greater than the second predetermined threshold (t 2); and - if the second adhesion value (μ 2) is lower than the first adhesion value (μ 1), determining that the adhesion curve between the wheels belonging to a plurality of controlled axles (A n) of a railway vehicle and the rail is an adhesion curve having a trend which has an adhesion peak (μ p) at a sliding value (δ p) lower than said first predetermined threshold (t 1).