The investigation describes the follow-up of the victims of the 1995 Tokyo sarin attack who were followed by a team at the St. Luke's International Hospital. A symptom questionnaire ("St. Luke's Questionnaire") was developed and given 2, 3, and 5 years following the sarin attack. Somatic and psychological symptoms have continued for 5 years after the incident. New post-traumatic stress disorder diagnostic criteria, which include physical symptoms, were developed and applied for assessment of the outcomes. The St. Luke's cohort was also compared with other Japanese sarin attack cohorts. Interventions, including counseling, medical treatments, and support group activities, were associated with fewer symptoms among the victims.