This research is concerned with studying personal pronouns in English and Arabic syntactically to point out the similarities and differences between the two languages under study as far as the accuracy of personal pronouns in expressing number system is concerned. This research hypothesizes that Arabic personal pronouns show greater accuracy and variety in describing number than English and this is mainly because English and Arabic belong to two different families. Hence, in order to give a clear insight of personal pronouns and their relation to number system, the research presents an adequate explanation of personal pronouns in both English and Arabic, followed by a comparison of the two languages under study by relying on two major descriptive models represented by Quirk, R.; Sidney, G.; Geoffrey, L. and Jan, S. (1985) for English and Aziz, Y. (1989) for Arabic. This research concludes that Arabic is more accurate in describing number system than English and this is simply because English and Arabic belong to two different families.