Introduction: Oil is a naturally occurring liquid found in rock formations. It consists of a complex mixture of hydrocarbons of various molecular weights plus other organic compounds. The workers in Aden (Yemen) Petroleum Refinery are exposed to a wide variety of hazards that may affect their health which can be broadly classified as; physical, chemical, biological, mechanical/ergonomics and psychological hazards. Aim of work: To identify the prevalence of work-related morbidities among Aden refinery workers and to study some associated correlates. Materials and methods: A cross sectional study was conducted in Aden Refinery Company (ARC), Alburigah district, Aden governorate, Republic of Yemen and included 398 workers. Data was collected by using semi structured questionnaire which included demographic data, detailed occupational history of the current and previous jobs, and history of work related illness. Results: The mean age of the studied workers was 42.91 ± 7.89 years. The study showed that allergy (e.g. occupational asthma, allergic rhinitis, skin allergy etc) is the most frequently recorded illness among the study participants (55.5%). Hypertension (42.2%) is the second common illness among them. Hypertension and cardiovascular diseases were statistically significant higher among smokers and those with work duration of ≥ 30 years. About one third (32.7%) of the studied sample had medical history of post-employment hearing defects which was statistically significant among those with work duration of ≥ 30 years, those who had history of noise exposure (37.5%) and those who were smokers. The current study also revealed that 8 cancer cases (2%) among the studied participants were rediagnosed post-employment. We also found that 10% of the workers were suffering from symptoms (fatigue, headache, nasal irritation and difficulty of breathing) during the working hours. Conclusion: Petroleum refinery workers are exposed to hazards that affect their health especially allergic diseases. These health effects were higher among smokers and those with long work duration (≥ 30 years).