BACKGROUND: Dental health care workers (DHCW's) are invariably at a higher risk of contracting COVID-19. The objectives were; to investigate the current knowledge on COVID-19 among the DHCW's; and to conduct quasi-experiment among the DHCW's who were unaware of the disseminated COVID-19 information. METHODS: A nationwide cross-sectional study targeting dental interns, auxiliaries, and specialists with a two-staged cluster sampling technique was performed. A 17-item questionnaire was subjected to reliability and validity tests before being administered. The participants for quasi-experiment were separated from the original sample after their initial response. Chi-square test assessed responses to knowledge statements between the participants. Difference in mean knowledge scores between the categories of DHCW's and sources of COVID-19 information was assessed using ANOVA. Data from the quasi experiment (pre vs post knowledge intervention) was subjected to paired t-test. Percentage of DHCWs providing correct or wrong responses to each knowledge statement at baseline and after 7 days were compared using McNemar test. RESULTS: The overall sample consisted of 706 (N) participants, and the DHCW's with no prior knowledge on COVID-19 (N=206) were part of the quasi experiment. Findings from cross-sectional study revealed that knowledge was significantly (p<0.05) related to the qualification level (interns vs auxiliaries vs specialists). However, the difference in the source of information (WHO/CDC vs Journal articles vs MoH) did not demonstrate any effect. Number of participants with correct responses to knowledge questions had significantly (p<0.05) increased after intervention. Also, the overall mean knowledge score (10.74+/-2.32 vs 12.47+/-1.68; p<0.001) had increased significantly after the intervention. CONCLUSION: In conclusion, the basic knowledge on COVID-19 among the DHCW's in Saudi Arabia is acceptable. Timely dissemination of information by the Ministry of Health, Saudi Arabia had a positive impact on the COVID-19 knowledge score of the DHCW's.