Objectives: To describe some clinical characteristics of Chiari malformation type I in adults. Subjects and methods: A retrospective, prospective, descriptive, and cross-sectional study on 45 adult patients (≥ 18 years of age) diagnosed Chiari I malformation and surgically treated at the Departments of Neurosurgery, Cho Ray Hospital from January 2016 to December 2019. Results: Mean age was 35.84 ± 9.35 years old. The average time from symptom onset to surgery was 16.42 ± 37.34 months. Clinical symptoms of Chiari I malformation varied, suboccipital headache and limb numbness were still the most common symptoms (48.89% and 64.44%, respectively). Tremor in limbs was 13.33%. Dizziness and nausea were encountered in 6.67%; 4.44% had balance disorder. Shortness of breath accounted for 2.22%; facial numbness pain 6.67% and hoarse voice 2.22%. In the group of symptoms of spinal cord compression, 2.22% had weakness and paralysis of the limbs, 2.22% of sensory disturbances, and 11.11% of muscle atrophy. Valsalva test was positive (2.22%). Conclusion: Clinical symptoms of Chiari I malformation varied, suboccipital headache and limb numbness were still the most common symptoms. Tremor, dizziness, nausea, balance disorder, shortness of breath, facial pain, hoarseness, weakness in limbs, sensory disturbances, muscle atrophy, and Valsalva were less commonly seen in our study. * Keywords: Chiari I malformation; Clinical characteristics; Adults.