['The relationship between beta2-adrenoceptor polymorphisms and bronchoprotective response with long-acting beta2-adrenoceptor agonists is unknown.', 'We retrospectively analysed data from six placebo-controlled randomized studies in corticosteroid treated asthmatics where formoterol or salmeterol were administered over a 1-2-week period, with prior 1-2 week washout, assessing the primary end point of methacholine PD20 and adenosine monophosphate PC20, following first and last dose, expressed as doubling dose difference from placebo.', 'There was no significant heterogeneity between the different studies. Patients who had homozygous or heterozygous genotypes containing the arginine-16 polymorphism (Arg16-Arg16 or Arg16-Gly16) had greater bronchoprotective subsensitivity compared with the homozygous glycine-16 genotype (Gly16-Gly16), amounting to a mean doubling dose difference of 1.49 (95% CI 0.50, 2.48), after the last dose. Subsensitivity of response was greater with formoterol than salmeterol after the last dose in all genotypes, especially with the arginine-16 polymorphism, amounting to a doubling dose difference of 3.00 (95% CI 1.01, 4.99) between formoterol and salmeterol.'] Does the arginine-16 beta2-adrenoceptor polymorphism predispose to bronchoprotective subsensitivity in patients treated with formoterol and salmeterol?