Introduction: Occupational lung diseases are some of the common causes of lung function impairment. Spirometry is a gold standard to determine lung function and, to diagnose obstructive and restrictive lung diseases. Therefore, this study aimed to determine the prevalence of abnormal lung function among employees of different industries of Bhutan. Methods: This retrospective study was carried out by retrieving all the spirometry findings and demographic variables of employees of different industries of Bhutan from the Spirometry Software of Respiratory Laboratory at the Center for Research in Respiratory and Neuroscience (CRRN), Khesar Gyalpo University of Medical Sciences of Bhutan (KGUSMB) . All these retrieved data were saved in Microsoft Excel and simple descriptive statistics were used to analyze the data and were expressed in numbers, percentages, mean and standard deviation. Results: Spirometry and demographic results of 3508 industrial employees were obtained. The mean age was 33.8years and mean BMI was 24.95 Kg/m2. Non-smokers comprised 79.9% (2804) of the total industrial employees. Abnormal forced expiratory volume between 25% and 75% of vital capacity (FEF25%-75%), a marker of small airway disease, constituted 24.1% (846) of the total industrial employees. Furthermore, 1.1% (39) had abnormal forced vital capacity (FVC), 1.3% (46) presented abnormal forced expiratory volume in 1 second (FEV1 ) and 1.5% (53) showed reduced FEV1 /FVC. Conclusions: Small airway impairment is common among industrial workers of Bhutan indicating presence of high prevalence of occupational lung diseases in its early stage which may potentially become clinically apparent after long latency.