The authors describe a 50-year-old man who was evaluated for a rigid spine syndrome with onset at age 15, and subsequent walking difficulties. Cardiac and pulmonary functions were normal. Deltoid biopsy revealed the presence of small vacuoles and increased glycogen with Periodic Acid Schiff staining in a limited number of fibers. Acid alpha-glucosidase staining was decreased in leucocytes, and genetic analysis identified the presence of two mutations in that gene. This observation suggests that Pompe disease should be considered in the differential diagnosis of rigid spine syndrome, even in patients without respiratory involvement or with a muscle biopsy showing only mild histopathological changes.