In this study we evaluated esophageal emptying using an isotope-labeled solid meal (an egg salad sandwich labeled with 99mTc-sulfur colloid) and compared it with lower esophageal sphincter pressure and a graded symptom score in the assessment of treatment in achalasia. Twenty-nine achalasic patients had lower esophageal sphincter pressure and esophageal emptying measured before treatment. Emptying at 5 min in the achalasic patients was significantly delayed, compared with normals (p less than 0.001), but did not correlate with resting lower esophageal sphincter pressure. After treatment lower esophageal sphincter pressure fell by 63% (p less than 0.01). A similar improvement was observed in esophageal emptying at 5 min after both pneumatic dilatation (63%, p less than 0.01) and surgery (70%, p less than 0.05). Percentage change in lower esophageal sphincter pressure and percentage change in esophageal emptying were significantly correlated (r = 0.76, p less than 0.01). There was also a significant correlation between symptom score and percentage change in both esophageal emptying (r = 0.70, p less than 0.05) and LES pressure (r = 0.77, p less than 0.05). Radionuclide measurement of esophageal emptying using a solid meal is a simple, noninvasive, and physiologic test of esophageal function. In achalasia, changes in emptying after treatment generally reflect the patient's clinical status and correlate with changes in lower esophageal sphincter pressure. The results suggest that radionuclide esophageal emptying of a solid meal may be a practical alternative to esophageal manometry in the assessment of treatment and may have an important future role as an objective parameter in comparing new treatment modalities.