Utilizing the rationale that the calcium channel blocker nifedipine decreases lower esophageal sphincter pressure, we performed a double-blind, placebo-controlled, crossover trial of sublingual nifedipine in achalasia, a disorder whose treatment depends on reduction in lower esophageal sphincter pressure. Ten patients participated in this trial, completed diaries, underwent manometric determinations of lower esophageal sphincter pressure, and had testing of esophageal emptying rates by a solid-meal radionuclide method. Nifedipine, titrated to a dose of 10-30 mg before meals, was well tolerated. Compared with placebo, nifedipine significantly reduced the frequency of dysphagia, but some symptoms of dysphagia, regurgitation, or nocturnal cough were still present most days. Nifedipine significantly reduced lower esophageal sphincter pressure by 28%, a value approximately one-half that achieved by successful pneumatic dilatation or myotomy. Esophageal emptying rates, as determined by the radionuclide method, were unchanged by nifedipine. We concluded that 1) nifedipine reduces symptoms of achalasia, but substantial symptoms do remain during such therapy; 2) the suboptimal effect results from the limited, although statistically significant, effect of nifedipine on reduction of lower esophageal sphincter pressure; and 3) although we believe that nifedipine may be recommended as treatment for achalasia in the subset of patients whose overall medical condition places them at high risk for forceful dilatation or surgery, it cannot be recommended as a standard alternative to these other modalities.