A cross sectional study was performed yearly, over a five year period, in six cotton and two manmade fibre textile mills. Each operative was administered a respiratory questionnaire and invited to perform spirometry, measurements of FEV₁ and FVC were recorded. Assessment of work area and personal dust exposures were also performed. Of the initial study population 510/991 (51.4%) operatives have been re-assessed at year five. The proportion of operatives at year five follow-up are similar in both the cotton and manmade fibre groups; cotton 282/553 (50.9%) compared to 228/438 (50.9%) in manmade fibre. In total, 322 of these operatives performed acceptable spirometry following the ATS guideline for both of the study years. Overall both measures of lung function decline were low and similar for both exposure groups; Cotton FEV₁= -13 mls/yr (95%CI -4,-21) FVC= -14 mls/yr (-4,-25) compared to manmade fibre FEV₁= -17 mls/yr ( -7,-26) FVC= -14 mls/yr (-3,-25). Within manmade fibre workers, multiple regression identified smoking as a predictive factor of increased decline in FEV₁. Within cotton, increased levels of personal dust exposure was predictive with a decline of FEV₁. The presence of work related respiratory symptoms was predictive with a decline in FVC.