Objective: A case series evaluating the acute effects of noninvasive positive pressure ventilation (NPPV) in patients with chronic hypercapnic respiratory failure (HRF) secondary to interstitial lung diseases (ILD). Patients and methods: Ten patients with ILD were retrospectively evaluated. All had restrictive lung function (mean TLC, 47.6 ± 12.6% predicted) and chronic hypercapnic respiratory failure (mean pH = 7.39 ± 0.02). Arterial blood gas analysis and lung function were compared before and after the application of controlled pressure-limited NPPV. Results: Daytime PaCO₂ during spontaneous breathing decreased by 5.4 ± 1.3 mmHg (95% confidence interval, 4.5-6.3), from 57.7 ± 5.1 mmHg to 52.3 ± 5.9 (p < 0.001); while daytime PaO₂ increased by 3.4 ± 3.3 mmHg (95% confidence interval, 1.0-5.8), from 63.7 ± 3.5 mmHg to 67.1 ± 3.4 (p = 0.01); and TLC increased by 3.9 ± 4.5% (95% confidence interval, 0.7-7.1), from 47.6 ± 12.6% mmHg to 51.5 ± 10.0% (p = 0.023). Conclusions: In patients with ILD and chronic HRF controlled NPPV is tolerated and can acutely improve blood gas levels. Further studies examining the long-term benefits need to be explored.