Background: Coronaviruses are enveloped virus with a high case fatality rate. Medical students are at risk of acquiring this lethal virus. Aim of the study: Assess the knowledge and attitude among medical students in King Abdulaziz University Hospital (KAUH). Methods: A cross sectional study was performed in (KAUH) on a 672 Medical students who were participate in this study. Knowledge and attitude were assessed by using self-administered, pretested questionnaire based on WHO guidelines. Descriptive statistics were carried out to express participants’ sociodemographic information, mean knowledge and mean attitude scores. Inferential statistics (p < 0.05) were used. Result: Our sample include 56.2% female and 43.8% males with mean age 21.91 ± 1.433 years. 49.9% of them have high social class. The mean knowledge score of the students was 10.32 ± 4.21 (based on 25 knowledge questions) which internet is the main source of their knowledge 19.5%. The mean attitude score was 8.53 ± 1.70 (based on 11 attitude questions). 51.4%, 57.1%, 51.4% of high knowledge were female, and in clinical years and who are lived in north Jeddah respectively. Also, positive attitude was noticed more in female 56.6%, students in clinical years 70.8%, and who are lived in north Jeddah 52.5%. Discussion: Data of the present research revealed that there is a statistically significant difference in students' knowledge according to their grade in college, age group, and social class (p<0.05) similarly to Muhammad, et al., 2014. While, there is a statistically significant difference in attitude of the studied sample according to their age group, and social class only (p<0.05) similarly to Mohamed O.et.al, 2015 Conclusions: Findings of this study showed that female medical students, high social class one and who are in clinical years in KAUH, in Jeddah Saudi Arabia have good knowledge and positive attitude towards MERS CoV more than others.