Changes in the daily living needs of 629 patients with advanced cancer were investigated (1) during and (2) 3 to 6 months after a course of outpatient chemotherapy and/or radiation treatment. The analytic sample consisted of patients completing both baseline and follow-up interviews [n = 434). At both times, the point prevalence of need and unmet need for assistance with personal care, instrumental activities, transportation, and home health tasks was calculated. In addition, the prevalence of new need and unmet need at follow-up was determined as were the rates of resolution of baseline need. The prevalence of need for assistance with personal care increased from 7% at baseline to 16% at follow-up; the dynamic of need acquisition and resolution resulted in relatively constant prevalence rates in other task areas. Acquisition of need at follow-up was associated primarily with disease and treatment-related characteristics. Approximately one third of patients reporting need for assistance during at least one interview did not have enough help. New unmet need at follow-up was associated most strongly with patients' mobility and the ability of their informal support system to provide care. The apparently rapid fluctuation in patients' experience of need and unmet need suggests the necessity for ongoing appraisal of patients' physical condition and social situation.