Internal control system is an important pillar in an organisation.Considering theevidence from major accounting fraud cases that occurred consequence to weakinternal control, such as Enron, it could also occur ina financial institution.Hence, the objective of this study is to investigate the bank managers’ opinion onthe likelihood of security threats in the computerised banking systems (CBS) inMalaysia. Since most major financial institutions operate in the capital city ofKuala Lumpur, questionnaires were sent toselectedbank branches in KualaLumpur. The findings are expected to provide a platform for bank managers toshare their threats’ experience. Secondly, to assist them in designing andformulating a sound and effective internal control system that will providereasonable assurance for achieving the bank’s mission. Findings are also expectedto provide general insights of internal control system, as most information is veryremote and confidential, thus generate a platform for promoting an efficient andeffective internal control practice in financial institutions.