Three non-parametric models are presented for describing the survival experience of patients with chronic disease. Model I assumes that two independent forces of mortality (disease specific and normal) act simultaneously on the total patient population. If after a number of intervals the observed survival experience approximates a normal level, a cure rate can be estimated and the survival pattern described according to Model II: ac-fraction subject only to normal mortality and a (1–c)-fraction subject to an additional mortality risk. If the observed survival appears to be stabilizing at a level somewhat lower than normal, the data fit Model III: a c′-fraction subject to a mortality risk somewhat higher than normal, and a (1–c′)-fraction subject to a high additional mortality risk. When there is no evidence of stabilization of interval survival rates, no cure rate can be estimated and only Model I is applicable. Models I and II can be considered as special cases of Model III.