We investigated an alleged association between ganglioside therapy and the risk of developing the Guillain-Barré syndrome (GBS) in a historical cohort study. Using official medical records of the Local Health Unit No. 31 of Ferrara Province, northern Italy, we linked data on sales of gangliosides with information regarding hospital admissions and discharge diagnoses between January 1, 1988, and May 31, 1990. The number of incidence cases of GBS observed within 30 days of gangliosides administration in a cohort of 13,373 treated subjects (0.0 cases) was not significantly different from that expected in the general population (0.014). Our study suggests that patients receiving gangliosides are not at increased risk of developing GBS. However, because of sample size limitations, these findings should be confirmed in a larger cohort study.