This study aims at investigating how borrowed nouns from English are inflected for plural and gender in Colloquial Saudi Arabic (CSA). The attempt is also made to account for the possible linguistic factors which may affect this inflection in light of some theories in morphology. The analysis is based on more than 250 loanwords collected from different sources (dictionaries, social, media, and TV series). The results showed that foreign nouns are found to be marked for all types of plural (broken plural (BP), female sound plural (FSP), and masculine sound plural (MSP)). More than 77% of borrowed nouns are inflected for FSP. However, this result disagrees with the plural formation rule operating in native nominal stems, which states that BP is the most common, and SP seldom occurs. Views from morphology theory as proposed by Abd-Rabbo (1990) and McCarthy and Prince (1990a; 1990b) were employed to account for this phenomenon. Another feature which is also peculiar to FSP formation is related to the attachment of "--ha:t" and "--ya:t" to singular borrowed nouns to form FSP instead of "--a:t." Like plural marking, gender assignment to borrowed nouns is also subject to the CSA rules. All English loan nouns are inflected either for masculine by attaching the [phi] morpheme (the unmarked) or feminine gender by attaching "--ah" (the marked). Out of the three functions of the feminine marker "--ah" introduced by Drozdík (1998), the inflectional function is the only function that is found at work within foreign nouns. The study concludes with recommendations for further research on loanword variation with regard to plural formation and other morpho-syntactic processes across the different dialects of Arabic.