This study aimed to investigate the pulmonary effects of methylmethacrylate (MMA) in a group of occupationally exposed workers. In the exposed group 20% had chronic cough compared with 1% in controls. Spirometric values at the beginning of the workshift were similar in both groups, but a mild airways obstruction appeared during the workshift. The maximum expiratory flow when 50% of the forced vital capacity remained to be exhaled (MEF50) and the ratio of MEF50 to maximal expiratory flow (MEF50/MEF) decreased significantly during the workshift among exposed workers v controls (p = 0.04 and 0.01 respectively). Results remained unaffected after adjustment for smoking. Exposure to MMA seems to be responsible for a mild airways obstruction but further study on a larger population would be useful.