The peritoneal equilibration test (PET) is a standard technique to assess p
eritoneal membrane characteristics and to analyze ultrafiltration failure i
n peritoneal dialysis patients. The measurement of weekly creatinine cleara
nce as well as calculation of Kt/V are important tools to assess adequacy o
f dialysis. This article gives an overview of the most important test metho
ds, how they should be performed, and how they are interpreted. Exact perfo
rmance is essential to get interpretable results, to prescribe adequate the
rapy and to diagnose dialysis-related complications as early as possible.