Acute gastric volvulus in infancy is a rare disorder and a surgical emergency. Prompt clinical suspicion and radiological assessment are essential for this life-threatening condition. We report a 3-month-old female case, admitted for an initial suspicion of an intestinal obstruction. She presented unproductive retching, respiratory distress, epigastric distension and lethargy. It was not possible to introduce a naso-gastric tube. A radiological contrast study showed an occluded cardio-esophageal junction without passage of barium, two gastric fluid levels and a horizontally positioned stomach occupying the inferior portion of the left hemithorax, suggesting a left diaphragmatic hernia. Laparotomy revealed an acute mesenterico-axial gastric volvulus with a left posterolateral diaphragmatic hernia. The stomach volvulus was untwisted, the diaphragmatic defect was repaired after reduction of the herniated contents and no gastropexy was done. At 3 and 6-months follow-up examination the infant was asymptomatic and thriving.