Lack of compliance with prescribed peritoneal dialysis (PD) therapy is a common cause of inadequate dialysis and poor outcomes. Because measurements of delivered doses are performed infrequently, the values obtained may not reflect actual delivered therapy. To evaluate compliance with therapy and to record accurate and complete treatment history for each patient undergoing automated PD, a memory card with the capability to track and store 2 months of treatment data was developed and incorporated into a commercial PD cycler. The memory card is brought to the clinic during the monthly visit. The data is downloaded into a personal computer (PC) with specific software. The following parameters can be retrieved and displayed as a graph or chart: the time of the exchange, length of the exchange, solution transit time, drain time, automated exchanges and last fill, inflow and drain volume, net ultrafiltration, and times of drain alarms. The data can be displayed as daily therapy, mean of therapy values, or total therapy. With the information available, the renal team can incorporate changes into the prescription and provide feedback to the patient based on his/her compliance record. The data can be transferred to a central data pool via modem. This data collection system can also be used for quality improvement, to model delivered therapy, and to compare compliance scores among centers and by cohorts of patients according to demographic or comorbid conditions.