Thymomas are rare malignant epithelial growths, constituting 20% of mediastinal tumours. Resection followed by irradiation may be employed in all thymomas except for stage 1 thymomas. Mediastinal irradiation is associated with coronary artery disease. The mean duration of presentation of post-irradiation coronary artery disease is 16 years (range 3-29 years). In our patient coronary artery disease was found only a year post irradiation. A 55 year old male who presented with complaints of dyspnoea, retrosternal chest pain and heaviness since one year underwent resection for malignant thymoma followed by radiotherapy. He presented with coronary artery disease a year after undergoing mediastinal irradiation. On follow-up, patient was treated successfully by coronary artery bypass graft. This case is an unusual occurrence and suggests that mediastinal irradiation may result in significant coronary artery disease as early as within one year.