Disruptions in physical activities (functional status) were measured over a 1-month period in 24 patients with non-small cell lung cancer with the Karnofsky Performance Status Index and two patient self-report measures. Changes over time were noted for the whole group, and mean scores of the treated subgroup were compared with an untreated cohort. Prior weight loss was significantly associated with baseline functional status. Age was not significantly associated with degree of functional disruption, though 42% of the sample was aged 65 years or older. The greatest disruptions in physical activity were noted in ambulation. A third of the sample had difficulty walking one block or more. Serious fatigue was experienced by 79% of the subjects and 44% had difficulty with household chores. Only 21% were completely satisfied with their level of activity. Pain improved in the treated subjects over time. Despite no significant differences at baseline, untreated subjects had more limitations in physical activities than treated subjects over time. All three instruments were significantly correlated. Careful monitoring of physical difficulties may help nurses focus interventions and decrease the physical distress associated with illness and treatment. In this study, those receiving chemotherapy did not experience significantly greater physical dysfunction. In fact, the untreated patients, who might not receive vigilant nursing assessment, demonstrated greater physical decline.