We aimed at investigating the distribution of dyspnea etiology in patients with normal cardiorespiratory function (NCF). We studied 57 pts. (33 male & 24 female) aged 58.4±7.8 yrs. who presented at the Outpatientsā€˜ Department during the past 12 months, complaining of breathlessness with no other respiratory symptoms. Patients compalained of either acute breathlessness (AB group- starting within the past 48 hrs.) or chronic (CB-group-more than 48 hrs. duration). All had a chest X-ray along with spirometry, arterial blood gases and heart ultrasound, having been rated as normal.Those in whom diagnosis was not primarily established, underent further testing including hormonal profile, lung perfusion scan, computerized chest tomography & angiography and respiratory muscle testing. In AB group (31 pts: 15 male & 19 female) aged 46.4±4.7 yrs. the final diagnosis was: 18 pts. (58%) acute psychogenic hyperventilation syndrome (HS), 11 (36%) anemia due to silent gastrointenstinal bleeding (GB) and 2 (6%) hyperthyroidism (HT). In CB group (26 pts:18 male & 8 female) aged 61.3±6.8 yrs. the final diagnosis was: 6 pts. (23%) HS, 7 (27%) GB, 3 (12%) obesity-deconditioning (OD, 3 (12%) anemia of renal failure syndrome (RF), 2 (8%), HT 2 (8%), diaphragmatric weakness (DW), 2 (8%) chronic thromboembolic pulmonary disease (TD) and 1 (2%) had brain tumor (BT). Our results indicate that patients with ²NCF²AB was most frequently due to either HS or GB while those with CB these diagnoses were less frequent. HS was more frequent in females while GB in males. Even with ²NCF², a minority of CB patients had DW or or TD which without specific testing might have been missed.