The internal audit function plays an increasingly important role for organizationsby evaluating internal controls, risk management processes and operationalperformance of organizations to recommend improvement activities. This function,which was traditionally performed within the organization, has gradually moved tothe outsourcing. This paper reviews published papers to find out the reasons foroutsourcing, outsourcing motives, disadvantages of outsourcing, outsourcers,outsourcing service providers and factors affecting the outsourcing of internal audit.From studying the boons or banes of outsourcing internal audit, the maincharacteristics of small and medium enterprises, the role of internal audit, assessingthe current status of internal audit performance of surveyed Vietnamses small andmedium enterprises, the paper proposes outsourcing for Vietnamese small andmedium enterprises.