Several reports have emphasized the rarity of hiatal hernia in achalasia, despite the lack of inherent incompatibility of the two conditions and despite the relatively high frequency of hiatal hernia in the general population. We reviewed the radiographs of 71 of 94 consecutive patients with manometrically proven achalasia referred to Yale-New Haven Hospital. Unequivocal hiatal hernia was seen in 10 (14.1%) patients and was seen in nine of 35 (25.7%) patients 51 years old or more. Review of the radiographic reports from these 10 patients indicated that only two were properly recognized as showing both achalasia and hiatal hernia. All five patients who underwent pneumatic dilatation had excellent results. We conclude that hiatal hernia in achalasia is frequently unrecognized and underreported but is not rare, with a frequency probably similar to that of the general population.