The Swedish prevalence of home mechanical ventilation is 8.2 per 100.000 with 10% annual increase. There is a large span (20 vs 2 per 100.000) between "top level" and "low level" counties, in spite of Sweden's homogeneous publicly financed system for provision of health care. The largest prevalence difference was found in patients with obstructive sleep apnoea syndrome (Pickwickian type), but their blood gas and lung function data were identical in top-level vs low-level counties. These data refute the hypothesis of overprescription in top-level counties. We conclude that the most probable explanation is under-recognition of patients in low-level counties.