A dialysis machine comprising - at least one input means that is configured to enable the input of parameters for at least one concentration of at least one dissolved substance in the vascular blood circuit of the patient; - a calculation unit that is configured to calculate and evaluate the development of the concentration change to be expected by the dialysis treatment and/or the end value of the concentration of said dissolved substance to be expected in the vascular blood circuit of the patient while providing a model at least including the previously input parameters or including an iterative calculation based on said parameters for at least one concentration of said dissolved substance in the vascular blood circuit of the patient in the form of the starting concentration of said dissolved substance and of the distribution volume of the patient, and including the dialysance or the clearance of said substance; and - control and/or regulation unit that is configured to output at least one signal and/or one display via output means and/or to influence the dialysis treatment in dependence on this evaluation; wherein - the control and/or regulation unit is configured to influence the settings for the dialysis treatment at the machine side with respect to the treatment duration, the dialyzate composition, the setting of the flow rates in the blood circuit and/or dialyzate circuit and/or the setting of the type of the dialysis treatment, wherein the dialyzate composition is preferably influenced by a control of a metering unit for a concentrate of dialyzate components and/or wherein the flow rate is influenced by a control of pumps of the blood circuit and/or dialyzate circuit. - at least one input means that is configured to enable the input of parameters for at least one concentration of at least one dissolved substance in the vascular blood circuit of the patient; - a calculation unit that is configured to calculate and evaluate the development of the concentration change to be expected by the dialysis treatment and/or the end value of the concentration of said dissolved substance to be expected in the vascular blood circuit of the patient while providing a model at least including the previously input parameters or including an iterative calculation based on said parameters for at least one concentration of said dissolved substance in the vascular blood circuit of the patient in the form of the starting concentration of said dissolved substance and of the distribution volume of the patient, and including the dialysance or the clearance of said substance; and - control and/or regulation unit that is configured to output at least one signal and/or one display via output means and/or to influence the dialysis treatment in dependence on this evaluation; wherein - the control and/or regulation unit is configured to influence the settings for the dialysis treatment at the machine side with respect to the treatment duration, the dialyzate composition, the setting of the flow rates in the blood circuit and/or dialyzate circuit and/or the setting of the type of the dialysis treatment, wherein the dialyzate composition is preferably influenced by a control of a metering unit for a concentrate of dialyzate components and/or wherein the flow rate is influenced by a control of pumps of the blood circuit and/or dialyzate circuit.