A pregnant Thai woman presented with progressive dysphagia starting from the gestational age of 18 weeks. Total parenteral nutrition was administered at 33 weeks of gestation due to severe malnutrition. The fetus was found to be growth restricted. Preliminary diagnosis was esophageal achalasia. Diagnostic and treatment options, including early delivery followed by surgical intervention, temporizing pneumatic dilation and intrasphincteric botulinum toxin injection, were discussed before endoscopic examination. The patient preferred temporizing treatments to prolong the pregnancy and to allow for an improvement of her nutritional status to facilitate postpartum recovery. Marked dilatation of the esophagus was found during esophagoscopy. Therefore, local injection of 80 U of botulinum toxin A was chosen over balloon dilation. The swallowing function improved soon after the treatment. The patient and the fetus started to gain weight. Subsequent sonographic examinations did not show any evidence of botulinum toxicity in the fetus. The baby was born at 36 weeks of gestation with an active respiration and preserved muscle tones. Breast-feeding was withheld. The patient remained asymptomatic for at least 6 weeks after delivery. There have been reports of an intentional use of botulinum toxin in selected cases of unremitting movement disorder during pregnancy. No deleterious effects to the mothers or the babies were found in local injection with limited dosage after the first trimester. The authors cannot encourage the routine administration of this neurotoxin for the treatment of achalasia during pregnancy. However, this report provides additional information of botulinum toxin use in pregnant women.