Investigated the degree to which chronic, life-threatening illness and its treatment interfere with continued involvements in valued activities and interests--that is, illness intrusiveness--and its impact on quality of life in end-stage renal disease. Data were collected on two occasions separated by a lag of 6 weeks. Mixed analyses of variance indicated that life domains were affected differentially across treatments. Perceived illness intrusiveness correlated significantly with treatment time requirements, uremic symptoms, intercurrent nonrenal illnesses, fatigue, and difficulties in daily activities. Significant quality-of-life differences were observed across treatment modalities for satisfaction/happiness and pessimism/illness-related concerns but not for depression/distress. Perceived illness intrusiveness correlated significantly with each of these quality-of-life measures. Results were stable over time. These findings substantiate the construct of illness intrusiveness as a mediator of the psychosocial impact of chronic, life-threatening illness.