Objective This study aimed to observe the late effects of ionizing radiation by medical follow-up(after 17 years) of the three patients('Ming','Jun','Lei') moderate bone marrow form of acute radiation sickness who accidentally were exposed to ⁶⁰Co.

Methods Changes in hematology, immunology, neurology, reproduction, lens, and cytogenetics were measured according to the medical follow-up plan.

Results All the three patients had chief complaints of being prone to cold, neurosis, and sexual dysfunction. They also had chronic conjunctivitis, decreased vision, as well as punctate and patchy opacity of ocular lens. The blood routine, liver function, renal function, and sex hormone were normal. The cellular immunity indexes CD3, CD4, CD8, and CD4/CD8 were decreased. The rate of chromosomal aberration(dicentric and fragment) and micronuclear decreased over time. 'Ming' and 'Jun' showed increased creatine kinase isoenzymes and myocardial ischemia, according to the electrocardiogram. 'Ming' had thyroid carcinoma 12 years after irradiation, and 'Lei' had thyroid nodules 14 years after the accident.

Conclusion The medical follow-up study collected data for long-term effects of acute radiation sickness patients and provided information for their late medical intervention.