Ventilated patients are at risk of acquiring ventilator-associated pneumonia. Various techniques are available for diagnosing ventilator-associated pneumonia including bronchoalveolar lavage, protected specimen brush and non-directed bronchoalveolar lavage. There is a paucity of evidence regarding the safety profile of these techniques, particularly non-directed bronchoalveolar lavage. This service evaluation aimed to establish whether non-directed bronchoalveolar lavage is a safe procedure. A prospective service evaluation of non-directed bronchoalveolar lavage on our adult intensive care unit was undertaken by a senior physiotherapist trained into carrying out the procedure, measuring pre- and post-procedure vital signs including heart rate (HR), tidal volume (VT), systolic blood pressure (SBP) and pulse oximetry (SpO2). Eighty-five episodes in 41 patients were included in the evaluation. There was a statistically significant difference between pre- and immediately post-procedure recordings for all vital signs measure. HR (min-1), means (SD) 87.1 (16.4), 91.5 (16.5), 87.5 (15.9), 87.7 (15.7) respectively pre, immediately, 5 min after and 30 min after procedure (P < 0.01). SBP mmHg, means (SD) 133.9 (26.1), 142.1 (25.6), 136.9 (25.3), 134.8 (23.4) pre, immediately, 5 min and 30 min after procedure (P < 0.01). VT mL, median (range) 0.523 (0.118–1.180), 0.512 (0.131–1.05), 0.519 (0.104–0.95), 0.534 (0.110–1.080) each pre, immediately, 5 min and 30 min post procedure (P < 0.05). SpO2 %, median (range) 98 (89–100), 100 (96–100), 98 (92–100), 97 (90–100) again each pre-, immediately post, 5 and 30 min post-procedure time-points (P < 0.0001). The statistically significant difference was not detected between pre-, 5 or 30 min post-procedure time-points. None of the changes observed were clinically significant and no untoward events happened to any of the subjects included. Non-directed bronchoalveolar lavage is a safe and inexpensive procedure that can be carried out easily in an intensive care setting by a trained physiotherapist, avoiding the need for invasive bronchoscopy.