Purpose: The purpose of the present study was to examine the current situation regarding sedative（mainly benzodiazepines）-related disorder in Japan and the clinical characteristics of Japanese patients with this disorder.
 Subjects : Subjects were 671 drug-related disorder patients diagnosed according to the ICD-10 classification as “F1: mental and behavioural disorders due to psychoactive substance use,”who abused psychoactive substances other than alcohol. Of all the psychiatric hospitals in Japan between September and October 2010,these drug-related disorder patients had consecutively consulted or were admitted to 153 psychiatric hospitals.
 Methods : The present study was conducted by means of a mail survey. Subjects’clinical information, including history of psychoactive substance use,means of access to the primary drug of abuse,other ICD-10 diagnoses including the F1 subcategory and comorbid psychiatric disorders, and recent history of self-destructive behavior,were collected from the attending psychiatrists of each subject. The data thus gathered concerning sedative-related disorder patients were compared with those of patients with methamphetamine-related disorder, which has been the most serious drug-related problem in Japan since the 1950s.
 Results : Out of the 671 subjects, 119 patients mainly abusing sedatives（SRD group）were identified,while 361 patients were identified as mainly abusing methamphetamine（MRD group）. The MRD group was the largest population（53.8% of the total subjects）, followed by the SRD group（17.7%）,and then the inhalant-related disorder group with 56 patients（8.3%）. Compared with the MRD group, the SRD group was younger, contained more female patients,and had a lower incidence of a history of involvement with anti-social societies and anti-social behavior. Patients in the SRD group were more likely to have started abusing drugs with the intention of reducing the unpleasant symptoms of insomnia（42.9%）, anxiety（26.1%）, and depression（16.0%）,and to acquire the drugs they abused from medical institutions such as psychiatric or primary care clinics（82.1%）, while patients in the MRD group were more likely to have started out of curiosity（35.1%）or in response to peer pressure（47.1%), and to acquire their drugs from a “pusher”（32.8%）. Additionally, in the SRD group, the ICD-10 F1 subcategory diagnoses that were the clinically most important were “dependence syndrome”（64.0%）,“harmful use”（16.2%）,and “acute intoxication”（16.2%）,while the most important subcategory diagnosis in the MRD group was “psychotic disorder”（34.3%）and “residual disorder and late-onset psychotic disorder”（32.9%）. Further, comorbid psychiatric disorders were more frequently found in the SRD group than in the MRD group ; notably, co-occurrence of mood disorder was found in 45.0% of the SRD group in contrast to the MRD group（11.9%）. Recent episodes of deliberate self-harm behavior were also more frequently found in the SRD group than the MRD group（33.6 vs. 10.5%, respectively）; the major means by which these patients harmed themselves was by overdosing on prescribed drugs（23.5 vs. 4.7%, respectively）.
 Conclusion : The present study suggests that sedative-related disorder is an important clinical issue in the field of drug-related disorders in Japan today, and that SRD patients may represent a distinct type of drug abuser whose clinical characteristics are different from those of MRD patients. The development and spread of treatment programs for“dependence syndrome”and “harmful use”will help SRD patients, and educating psychiatrists about SRD will help prevent future sedative abuse.