Eighty dock workers handling grains and other cargoes were surveyed by respiratory and occupational questionnaires, spirometry, skin tests with common allergens and grain extracts, and serological tests. Sixty-nine of the men reported chest symptoms during exposure to barley dust and 13 men reported evening feverish episodes after handling barley. Symptoms were not related to smoking or atopic status. No gross deficits in lung function were detected. Six men handling barley and four handling non-dusty cargoes had their lung function measured over two working days. Falls in ventilatory capacity occurred in the six workers handling barley but not in the four handling non-dusty cargoes. Six previously unexposed subjects spent 2 h in a barley dust atmosphere of a silo and had lung function measured before and after the exposure. All subjects had falls in ventilatory capacity. In four these lasted 24 h or more and were associated with systemic symptoms. As with cotton dust the agent(s) responsible for symptoms from grain dust exposure remains uncertain. Our findings on the dock workers suggest that specific immunological responses are not involved.