Sanctioning of administrative violations is considered an effective solution in the struggle and prevention of administrative violations; it includes application of sanction forms, remedial measures with respect to individuals and organizations committing acts of administrative violations which are implemented by the competent persons. Among the sanctions imposed for administrative violations, warning is a special form of sanctions and is commonly applied in the fields of state management. The paper analyzes the theoretical and legal issues about the form of warning sanction in accordance with the Vietnamese law, shows some shortcomings on the regulation of this sanction and makes proposals for improvement.