Introduction: Albeit physical activity (PA) has an important role concerning the health of patients with chronic respiratory diseases, it remains unclear how PA patterns compare among different diseases. Aims: To compare PA levels of 3 major chronic respiratory conditions (Asthma, COPD and idiopathic pulmonary fibrosis [IPF]); and to analyze PA behaviour in the diseases’ subgroups (mild/moderate and severe/very severe). Methods: Stable subjects who did not perform pulmonary rehabilitation in the previous year were included. Patients were divided into subgroups according to diseases’ severity. The study’s primary outcome was PA in daily life (Actigraph GT3x; variable: steps/day) measured during one week over 12 h/day; other assessments included pulmonary function, exercise capacity, peripheral muscle strength and quality of life. Comparisons among (sub)groups were corrected for age, BMI and sex. Results: 107 subjects (52 asthma, 46[38-60]years; 31 COPD, 64[58-70]years; 24 IPF, 66[56-71]years) were studied. Subjects with asthma had higher PA levels than those with COPD and IPF (Table 1). No statistical differences in PA were seen among mild subgroups of patients (Table 2). Severe IPF patients had the lowest PA levels among the studied subjects (Table 3). Conclusions: Subjects with asthma have higher PA levels than COPD and IPF. Subjects with severe IPF are the most physically inactive patients.