Intrathoracic stomach is a rare finding. The real value of the high-resolution manometry (HRM) in the preoperative evaluation of these patients has not yet being fully tested. This study aims to evaluate: 1) the HRM pattern of patients with an intrathoracic stomach; and 2) HRM findings as predictors for prosthetic reinforcement of the hiatus. We reviewed 33 patients (27 women, mean age 66 years) with an intrathoracic stomach who underwent HRM. Fifteen patients did the HRM as part of preoperative workup and were operated on in our institution. All patients were submitted to a laparoscopic Nissen fundoplication. HRM results show that the lower esophageal sphincter (LES) was transposed in all patients. Hiatal hernia was diagnosed in 21 (63%) patients. The length of the hernia was 4 ± 2 cm (range, 1 to 9 cm). LES oscillation was observed in 23 (69%) patients with a mean of 1 ± 0.4 cm (range, 0.4 to 2 cm). Hiatal mesh reinforcement was necessary in five (33%) of the operated patients. HRM findings did not predict hiatal mesh reinforcement. Our results show that: 1) HRM has a poor sensibility for hiatal hernia diagnosis; 2) half of the patients with an intrathoracic stomach have a normal HRM; and 3) HRM does not predict mesh hiatal hernia repair.