This study aimed to compare the impact of dyspnea, pain, and fatigue on daily life activities in ambulatory patients with advanced lung cancer. One hundred seventy-one outpatients with advanced lung cancer completed a questionnaire about symptom severity and whether symptoms interfered with daily life activities (normal work, walking, sleep, mood, relation with other people, enjoyment of life, and general activities). The results indicated that 1) dyspnea and fatigue interfered with at least one daily life activity in more than half the patients, and pain in about 40%, 2) dyspnea and fatigue interfered predominantly with physical activities, such as walking and work, whereas pain interfered with all activities almost equally, and 3) symptoms rated as low severity (1 to 3 on a 0-10-point numerical scale) were severe enough to interfere with at least one daily life activity. To recognize the impact of symptoms may contribute to provide better management.