A system for determining treatment-related data for the administration of at least one drug to a patient to be treated, comprising: - at least one sampling device for continuously and successively taking quantities of blood from the patient in order to obtain a plurality of blood samples (2, 3; 17-20); - multiple blood value measuring devices (4, 5, 15, 16) in order to measure blood values of the blood samples (2, 3; 17-20) taken and to obtain blood value measurement data sets (6, 7; 21 a-d); and - at least one calculating device (22; 9) for calculating the treatment-related data from the blood value measurement data sets (6, 7; 21 a-d) and, if appropriate, further data, wherein at least one patient-related first identifier and one time-related second identifier concerning the point of time of taking the blood sample (2, 3; 17-20) is assigned to each blood sample (2, 3; 17-20) and to each blood value measurement data set (6, 7; 21a-d) associated therewith, characterized in that by means of a first evaluation unit, the calculating device (22; 9) for calculation of the treatment-related data assigns at least one individual weighting factor, preferably a numerical factor, to each blood value measurement data set (6, 7; 21 a-d) with the same first identifier and a different second identifier in order to characterize a weighting of the blood value measurement data (6, 7; 21a-d) in the calculation operation; an assigning device is provided which is connected to each blood value measuring device (4, 5, 15, 16) in order to assign a third identifier related to the measuring equipment, being assigned to the particular blood value measuring devices (4, 5, 15, 16), and a fourth identifier related to the measurement accuracy to each blood value measurement data set (6, 7; 21a-d); and a second evaluation unit is provided in order to assign at least one individual weighting factor, preferably a numerical factor, for characterizing a weighting of the blood value measurement data in the calculation operation to each blood value measurement data set (6, 7; 21 a-d) with the same first identifier and a different fourth identifier. - at least one sampling device for continuously and successively taking quantities of blood from the patient in order to obtain a plurality of blood samples (2, 3; 17-20); - multiple blood value measuring devices (4, 5, 15, 16) in order to measure blood values of the blood samples (2, 3; 17-20) taken and to obtain blood value measurement data sets (6, 7; 21 a-d); and - at least one calculating device (22; 9) for calculating the treatment-related data from the blood value measurement data sets (6, 7; 21 a-d) and, if appropriate, further data, wherein at least one patient-related first identifier and one time-related second identifier concerning the point of time of taking the blood sample (2, 3; 17-20) is assigned to each blood sample (2, 3; 17-20) and to each blood value measurement data set (6, 7; 21a-d) associated therewith, characterized in that by means of a first evaluation unit, the calculating device (22; 9) for calculation of the treatment-related data assigns at least one individual weighting factor, preferably a numerical factor, to each blood value measurement data set (6, 7; 21 a-d) with the same first identifier and a different second identifier in order to characterize a weighting of the blood value measurement data (6, 7; 21a-d) in the calculation operation; an assigning device is provided which is connected to each blood value measuring device (4, 5, 15, 16) in order to assign a third identifier related to the measuring equipment, being assigned to the particular blood value measuring devices (4, 5, 15, 16), and a fourth identifier related to the measurement accuracy to each blood value measurement data set (6, 7; 21a-d); and a second evaluation unit is provided in order to assign at least one individual weighting factor, preferably a numerical factor, for characterizing a weighting of the blood value measurement data in the calculation operation to each blood value measurement data set (6, 7; 21 a-d) with the same first identifier and a different fourth identifier.