Immediate adverse reactions to anaesthetics have an immune mechanism in more than 50% of the cases. They are mainly due to muscle relaxant drugs. A prospective evaluation of tryptase, histamine and serotonin for diagnosing anaphylaxis to anaesthetics was performed over 2 years. The sensitivity of each marker was at 60-70% and it reached 80% when combining tryptase and histamine. Specific IgE have been already observed in serum from patients allergic to muscle relaxant, thiopentone, morphine, phenoperidine, propofol and radio-contrast media. However, the recent progress in the identification of drug epitopes by Sepharose-solid drug phase IgE radioimmunoassay has to be reconsidered as non-specific binding of hydrophobic drugs such as propofol to hydrophobic serum IgE has been observed recently in patients with drug allergy. In addition, association of drugs such as propofol and muscle relaxant may potentiate the mediator release by a non-elucidated mechanism.