BACKGROUND: Overweight and obesity are considered major risk factors for many diseases, and their prevalence is known to be high in Kuwait from previous studies. AIM: To assess the prevalence of overweight and obesity and related risk factors among Kuwait Oil Company (KOC) employees. METHOD: A cross-sectional study of full-time KOC employees was carried out using a structured questionnaire that was completed during periodic medical examinations. The questionnaire included demographic details, frequency and duration of physical activity, history of chronic diseases and medication. All participants were counselled and examined. Blood pressure, body mass index and fasting glucose were recorded. RESULTS: Some 3282 out of 3900 employees completed the study; 85% of participants were male, 62%were field workers and 38%were office workers. The overall prevalence of overweight and obesity among KOC employees was 75%. Males showed a higher level of overweight and obesity (79%) than females (56%). Field workers had a higher level of overweight and obesity (78%) and higher inactivity (65%) than office workers (72% and 56%, respectively). CONCLUSION: Overweight and obesity, together with inactivity, are highly prevalent among KOC employees, and more so among field workers than office workers. Encouraging an active lifestyle, healthy eating habits and weight control programmes are all possible interventions to reduce the prevalence of overweight and obesity.