Blood cadmium concentrations were determined in 377 adults, 297 men and 80 women, randomly selected from the Rabat Transfusion Center, Morocco. The mean blood cadmium level was 1.1+/-0.7 microg/l, which was higher than in French subjects, with an average of 0.7+/-0.6 microg/l. In Moroccan people, the mean blood cadmium concentration of men, 1.1+/-0.8 microg/l, was significantly higher than that of women, 0.8+/-0.4 microg/l, whereas in the French people tested, there was no statistically significant difference between men and women. In Morocco, employment of men and the smoking habits of men and women were linked to an increase of blood cadmium levels. The significantly higher level observed in men could be due to a higher percentage of men who were smokers and to professional activity leading to increased exposure to cadmium.