This invention relates to a device for peritoneal dialysis with a means for the regular discharge and reuptake of dialysate, which comprises a conduit with a catheter, wherein a measurement bag is present, in which dialysate can be introduced, wherein first means are provided, with which the static pressure in the conduit between catheter and measurement bag can be determined, and second means are provided, by means of which the dialysate volume flow can be introduced into the measurement bag for a certain period. In accordance with the invention, third means are present, by means of which the volume of the dialysate introduced into the measurement bag can be determined, and furthermore fourth means are present, by which the catheter resistance substantially can be calculated from the values determined by the first to third means.