Deaf and hard of hearing (DHH) children show difficulties in their morphosyntactic abilities. Purpose: The current study aimed to examine morphosyntactic errors in sentences produced by DHH students, who are signers of Israeli Sign Language, and also users of Palestinian Colloquial Arabic (PCA) and written Modern Standard Arabic (MSA). Method: Nineteen school-age DHH students participated in a sentence elicitation task in which they retold events portrayed in 24 videos in PCA and MSA. A control group of 19 hearing students was tested with the same task. Sentences in each language variety were coded for grammatical versus ungrammatical productions and for type of morphosyntactic errors for the latter. In addition, code-switched words were counted. Results: The hearing group showed no morphosyntactic errors, whereas the DHH students showed morphosyntactic errors in both PCA and MSA. In addition, both groups code-switched in both PCA and MSA, with more code-switching in the MSA task than in the PCA task. Furthermore, an interaction with age revealed that young students code-switched more in MSA and older students code-switched more in PCA. Conclusions: It is suggested that the morphosyntactic abilities of DHH students are incomplete in both language varieties. Lack of spoken language input may negatively influence the acquisition of spoken language, which impacts further the acquisition of the standard language in diglossic contexts. Code-switching is explained as both due to lexical gaps, when occurring in MSA, and an effort to raise the register in PCA.