An endosseous single tooth implant for a fixed tooth replacement, comprising a. a substantially cylindrical base body, which can be inserted into a bore made in a jaw bone, said base body having an annular recess, a positively locking portion and a bore which is open towards its coronal end and which is arranged cervically relative to the recess and which has a threaded portion which is arranged at the cervical end in the base body for fixing a holding screw, b. an abutment which can be inserted into the recess of the base body, said abutment having a positively locking portion, a bore for receiving the holding screw and a fixing head for the tooth replacement, and c. a holding screw which can be inserted into the blind bore in the base body and which passes through the abutment, wherein the positively locking portion of the base body has at least one base body positively locking element operative in the peripheral direction and the positively locking portion of the abutment has at least one abutment positively locking element complementary to the base body positively locking element, wherein the positively locking portion of the base body and the positively locking portion of the abutment are complementary to each other in such a shape that the abutment can be so inserted into the recess in the base body that the respective positively locking elements are brought into engagement with each other, wherein the mutually complementary positively locking elements (22, 26; 54, 66; 28, 53; 68) are in the form of a male part-female part connection in the manner of a spring leg - groove connection so that a spring leg (26; 53), which extends parallel to the longitudinal axis of the base body and which is provided on a component of the base body or the abutment, engages in rotationally-secured relationship into a corresponding groove (28; 54) on the other component wherein the spring leg is in the form of a pin held in a holding groove. a. a substantially cylindrical base body, which can be inserted into a bore made in a jaw bone, said base body having an annular recess, a positively locking portion and a bore which is open towards its coronal end and which is arranged cervically relative to the recess and which has a threaded portion which is arranged at the cervical end in the base body for fixing a holding screw, b. an abutment which can be inserted into the recess of the base body, said abutment having a positively locking portion, a bore for receiving the holding screw and a fixing head for the tooth replacement, and c. a holding screw which can be inserted into the blind bore in the base body and which passes through the abutment, wherein the positively locking portion of the base body has at least one base body positively locking element operative in the peripheral direction and the positively locking portion of the abutment has at least one abutment positively locking element complementary to the base body positively locking element, wherein the positively locking portion of the base body and the positively locking portion of the abutment are complementary to each other in such a shape that the abutment can be so inserted into the recess in the base body that the respective positively locking elements are brought into engagement with each other, wherein the mutually complementary positively locking elements (22, 26; 54, 66; 28, 53; 68) are in the form of a male part-female part connection in the manner of a spring leg - groove connection so that a spring leg (26; 53), which extends parallel to the longitudinal axis of the base body and which is provided on a component of the base body or the abutment, engages in rotationally-secured relationship into a corresponding groove (28; 54) on the other component wherein the spring leg is in the form of a pin held in a holding groove.