Two latex (Hevea brasiliensis) raw materials, one from the cytosolic fraction, the other from the total natural latex have been characterised by immunoblotting techniques. The two latex fractions A and B were studied by immunoprints using eight sera from patients who were allergic to latex. They gave different profiles though there were also allergens of common molecular weights (60, 35, 30, 25, 20, 18, 15, and 10 kD). This study confirms the importance of allergic reactions to latex, that may in some patients cause anaphylactic shock.