Background: Guillain-Barré syndrome (GBS) is a heterogeneous group of autoimmune polyradiculopathies, in which disease biomarkers, and outcome predictors are under continuous research. Material and methods: Thirty-three patients with GBS (12 females/21 males) aged between 24 and 73 years were assessed, using clinical data, Modified ERASMUS GBS Outcome (MEGOS) score and electromyography (EMG). Results: The average age of onset was 52.1 ± 12 years. The mean time period before hospitalization was 15 days. Clinical symptoms at onset were areflexia (24%), paresthesia (25%), weakness in the legs (36%) and arms (22%). 15 patients (45.4%) had cranial nerves involvement, while 11 (33%) developed respiratory failure of which five (15%) required mechanical ventilation. EMG revealed myelinopathy in majority of the patients – 19 (70%), axonopathy – 6 (22%), and axonomyelinopathy – 2 (8%). 27 (81%) patients received plasmapheresis, 2 (6.06%) – plasmapheresis with immunoglobulins, and 6 (18%) received no plasmapheresis due to contraindications. Treatment outcomes were as follows: 29 (88%) patients saw improvement, 2 (6.06%) had stable disease. There were 2 (6.06%) deaths in the cohort. Mean MEGOS was 4.0 ± 2 (male 5.0 ± 2; female 4.0 ± 2). Patients with myelinopathy and axonomyelinopathy had a higher MEGOS. Hospitalization delay and higher MEGOS score correlated with more severe disease evolution. Conclusions: Patients with delayed hospitalization, predominantly men, who had myelinopathy and mixed forms of GBS have a less favorable prognosis of the disease. Increased attention to the onset of symptoms consistent with GBS is needed in order to ensure a prompt diagnosis and hospitalization, as well as specialized treatment.