Bush bean plants (Phaseolus vulgaris L. cv. Contender) were treated once a week for six weeks with simulated acid mist at five pH ranging from 5.5 to 2.0. Leaf injury developed on plants exposed to acid concentrations below pH 3 and many leaves developed a flecking symptom similar to that caused by ozone. An adaxial, interveinal bleached area resembling SO2 injury also developed on some trifoliate leaves at the low pH treatments. Microscopic observations of injured trifoliates indicated that the palisade cells were plasmolyzed and that the chloroplasts lost structural integrity. Reductions in plant weight and chlorophyll content were detected across the pH gradient. Seed and pod growth were reduced at some intermediate acid depositions even though no visible foliar injury developed. Foliar losses of nitrogen, calcium, magnesium and phosphorus increased with decreases in acid mist pH, whereas foliar potassium concentrations were unaffected by acid mist treatment.