The main objective of this study is to examine the role of accounting information system in a company. Data for this study were collected from both primary and secondary sources. Primary data was collected through structured questionnaires, in- depth interview and sometimes personal questioning out of curiosity. Secondary date was obtained from records in the Administration and Finance department, Human resource department, shipping department, operations department, and the resulting data was analyzed using a simple table and percentages. The results show that accounting information system has a vital role in TEFON OILDFIELD Services Ltd Company (Case study). The various functions of decision making, planning, control, data analysis, communication, and reporting were amongst. Again from the findings, it can be seen that the system will become more effective and productive if the other departments could use it for data analysis. However, this can only be possible if all other departments not just the accounting and finance departments fully understand the system and can use it without any difficulty. My results certainly shown that very little is known on the Accounting Information systems as propounded by my findings and also in the accounting department of Tefon. They certainly agree it is very important but almost inexistent in Tefon.