We report some preliminary results of a study carried out in ten patients observed during headache attack and concerning particularly the plasma values of beta-ELI after acetylsalicylic acid (lysini acetylsalicylas: i.v. 1.8 g) administration. Blood samples for beta-ELI determination were drawn every ten minutes for 30 minutes beginning at time of drug administration. Plasma was immediately separated and stored at -20 degrees C until assayed. Lysini acetylsalicylas administration gave in our subjects a significant relief from pain, with a disappearance of headache in all cases. We showed, in comparison with basal conditions, increased-plasma beta-ELI values after drug administration. The levels of pain were evaluated by the analogic visual scale.