The flow-volume (F-V) curves and routine ventilatory functions were determined on 265 healthy male and female farmers in the suburbs of Chengdu. Compared with normal sedentary persons, the flows at high and middle lung volumes in farmers were reduced, but those at low lung volumes were increased; besides, these phenomena became more prominent with aging. The same ventilatory functions were performed with forward bending of neck and trunk in 4 healthy volunteers to mimic the working posture of farmers. Three of them had the same tendency with farmers. These suggested that the change of flow pattern in farmers is closely related to the working posture. The theoretical and practical significance of the "wave speed theory of flow limitation" proposed by Dawson is preliminarily identified by these facts.