Information on adverse health effects of occupational exposures to sodium sulfate dust is lacking. A study was conducted on 119 workers from five sodium sulfate surface solution mines in Saskatchewan. The investigation involved the older workers and the workers at highest dust exposure levels and included general medical screening with emphasis on the existence of hypertension, edema, calcium tetany, anemia, common skin problems, nasal septum perforation, persistent diarrhea; lung function tests; serum analyses for sulfate, calcium, sodium, and chloride content; and urinary inorganic sulfate output. All measured properties, including lung function, serum sulfate, calcium and electrolytes, were found to be within normal ranges. Forty- two workers with more than 10 years exposure experience show no significant differences in these properties compared to 77 workers with less than 10 years exposure experience. No abnormality could be discovered that might be related to such exposure.