This study aimed to ascertain the current level of writing apprehension experienced by Saudi prospective EFL teachers and their current level of essay writing ability. It also aimed to assess the impact of peer reviewing on their writing apprehension level and essay writing ability. Data collection was carried out via two instruments: Second Language Writing Anxiety Inventory (SLWAI) (Cheng, 2004) and an essay writing test. Reliability and validity of the two instruments were verified. The study sample consisted of 40 EFL major prospective teachers at Taibah University, KSA. These were equally divided into two groups: control (n=20) and experimental (n=20). Both groups were similar in terms of academic level, mother tongue background, and target language proficiency. The experimental group participants were introduced to peer-reviewing essay writing sessions while the control group participants were taught through the traditional teacher feedback-based essay writing. Results of data analysis showed positive impacts of peer reviewing on experimental group participants' writing apprehension and essay writing ability. Implications for using peer reviewing in ESL writing were discussed. (Contains 1 figure and 7 tables.)