The effect of nifedipine on subjective symptoms and objective dermographometer induced whealing was assessed independently in two double-blind crossover trials in which active drug or placebo were taken for 2 weeks. The lower dose study used nifedipine 5 mg 3 times daily and gave rise to symptomatic improvement as assessed by diary card and visual analogue scale in 5 of 11 patients. This was not statistically significant and was not accompanied by a reduction in dermographometer-induced wheal and flare responses except at highest pressures. In a separate study 7 patients were treated with nifedipine 10 mg 3 times daily. No change in whealing occured, 3 patients’ symptoms became worse and only 1 showed symptomatic improvement on nifedipine. Side effects were frequent at this dose. The reasons for the unfavourable response despite in vitro evidence for inhibition of mast cell degranulation by this drug are discusse