Many studies have been conducted on code-switching worldwide, but few were carried out on Saudi context. Therefore, this study inquires the use of code-switching among Saudis who speak both Arabic and English to identify the reasons of code-switching and to know the significant differences regarding gender, age, qualification, and level of English. The study raises two questions. They are: 1) What are the reasons of code-switching of Saudis as native speakers of Arabic? And 2) Are there significant differences for code-switching of Saudis as native speakers of Arabic due to gender, age, qualification, and level of English? A descriptive-analytical approach has been adopted, and SPSS program is used. A questionnaire (30 items) was distributed to a sample of 426 Saudis. Findings showed that those with high-level proficiency combined Arabic and English languages more due to their awareness of English language expressions and found English vocabulary more expressive and delivered their ideas better. Moreover, working people used code-switching extensively. Furthermore, postgraduates were found to be better than others. Additionally, genders were both exposed to the same circumstances. Finally, individuals among all age groups combined both Arabic and English languages due perhaps to several reasons. Therefore, the researcher recommends that it might be better to study the significance of forming training courses to keep the interest of natives to take pride and use it in all aspects of life. Finally, the researcher suggests conducting another study on investigating code-switching among instructors in EFL classrooms and exploring code-mixing since there are few studies.