This study aimed to identify certain occupational risk factors for stress among healthcare workers (HCWs) during the COVID-19 pandemic. Using a multistage random sampling approach, an online questionnaire was applied to collect data on role conflict and ambiguity, self-esteem and social support from 1378 HCWs working in primary health centers (regular and fever clinics; clinics specialized in managing patients with COVID-19 symptoms) across Saudi Arabia. The results showed that stress correlated positively with role conflict and ambiguity and negatively with social support. HCWs in fever clinics exhibited significantly more stress and role conflict and ambiguity than those who were working in regular primary healthcare centers. In conclusion, role conflict and ambiguity and social support were determinants for stress among HCWs, especially those working in fever clinics.