Introduction: Conventional Chest Physiotherapy (CCPT) remains the mainstay of treatment for sputum mobilization in patients with productive cough such as bronchiectasis and “Chronic Obstructive Airway Disease” (COPD). However CCPT is time consuming requires the assistance of a physiotherapist and limits the independence of the patient. Mechanical percussors which are electrical devices used to provide percussion to the external chest wall might provide autonomy and greater compliance. We compared safety and efficacy of a mechanical chest percusser devised by Formedic Technology with conventional chest percussion. Methods: Twenty patients (mean age 64years) were randomly assigned to receive either CCPT or mechanical percussor on the first day and crossed over by “Latin square randomisation” to alternative treatment for 6 consecutive days and the amount of sputum expectorated was compared by dry and wet weight. Adverse events and willingness to use was assessed by a home diary and a questionnaire. Results: There were 13 males and 7 females, eight diagnosed as bronchiectasis and 12 COPD. The mean dry weight of sputum induced by CCPT (0.54g + 0.32) was significantly more compared with MP (0.40g + 0.11); p-value = 0.002. The mean wet weight of sputum with CCPT (10.71g + 8.70) was also significantly more compared with MP (5.99g + 4.5); p-value < 0.001. There were no significant difference in adverse events and majority of patients were willing to use the device by themselves. Conclusion: The mechanical percussor although produces less sputum is well tolerated and can be a useful adjunct to CCPT