A bicompartmental or bicondylar knee prosthesis (100, 100') adapted to be fixed to a femur, the prosthesis (100, 100') comprising a medial portion (1, 1') adapted to define at least part of a medial femoral condyle; a lateral portion (2, 2') adapted to define at least part of a lateral femoral condyle; an interconnecting portion (3, 3') which integrally connects the medial portion (1, 1') and the lateral portion (2, 2') to each other; the prosthesis (100, 100') being shaped so as to be adapted to leave the native trochlea at least partially uncovered; wherein said medial portion (1, 1') and said lateral portion (2, 2') of the prosthesis (100, 100') comprise a respective posterior end part (11, 21, 11', 21'); said posterior end parts (11, 21, 11', 21') being destined to be posterior parts of the prosthesis (100, 100'), when it is implanted and the knee is in extension; wherein the medial portion (1, 1') and the lateral portion (2, 2') comprise a respective anterior end part (116, 116', 216, 216'), destined to be anterior parts of the prosthesis (100, 100'), when it is implanted and the knee is in extension; wherein the posterior end part (11, 11') of the medial portion (1, 1') has a posterior end and the posterior end part (21, 21') of the lateral portion (2, 2') has a posterior end; wherein the anterior end part of the medial portion (1, 1') has an anterior end and the anterior end part of the lateral portion (2, 2') has an anterior end; characterized in that, along a same axis, a length of the medial portion (1, 1') is greater than a length of the lateral portion (2, 2'), so that when the prosthesis (100, 100') is implanted said anterior end of the lateral portion (2, 2') is more distal than said anterior end of the medial portion (1, 1'); said axis being an axis perpendicular to a tangent to an outer surface of each of said posterior end parts (11, 21, 11', 21'), and perpendicular to tangents (t1, t2) to the anterior end (119, 219) of the medial portion (1, 1') and of the lateral portion (2, 2'), respectively. a medial portion (1, 1') adapted to define at least part of a medial femoral condyle; a lateral portion (2, 2') adapted to define at least part of a lateral femoral condyle; an interconnecting portion (3, 3') which integrally connects the medial portion (1, 1') and the lateral portion (2, 2') to each other; the prosthesis (100, 100') being shaped so as to be adapted to leave the native trochlea at least partially uncovered; wherein said medial portion (1, 1') and said lateral portion (2, 2') of the prosthesis (100, 100') comprise a respective posterior end part (11, 21, 11', 21'); said posterior end parts (11, 21, 11', 21') being destined to be posterior parts of the prosthesis (100, 100'), when it is implanted and the knee is in extension; wherein the medial portion (1, 1') and the lateral portion (2, 2') comprise a respective anterior end part (116, 116', 216, 216'), destined to be anterior parts of the prosthesis (100, 100'), when it is implanted and the knee is in extension; wherein the posterior end part (11, 11') of the medial portion (1, 1') has a posterior end and the posterior end part (21, 21') of the lateral portion (2, 2') has a posterior end; wherein the anterior end part of the medial portion (1, 1') has an anterior end and the anterior end part of the lateral portion (2, 2') has an anterior end; characterized in that, along a same axis, a length of the medial portion (1, 1') is greater than a length of the lateral portion (2, 2'), so that when the prosthesis (100, 100') is implanted said anterior end of the lateral portion (2, 2') is more distal than said anterior end of the medial portion (1, 1'); said axis being an axis perpendicular to a tangent to an outer surface of each of said posterior end parts (11, 21, 11', 21'), and perpendicular to tangents (t1, t2) to the anterior end (119, 219) of the medial portion (1, 1') and of the lateral portion (2, 2'), respectively.