본 연구는 3-methylpentane에 대한 흡입유해성을 평가하여 국제연합에서 정하는 화학물질의 분류 및 표지에 관한 세계조화시스템(Globally harmonized system, GHS)지침 및 고용노동부고시 제2013-37호에 따른 3-methylpentane의 화학물질 분류 표시 자료를 생산하기 위하여 OECD 화학물질 시험가이드라인 아급성흡입독성시험 TG 412(Subacute inhalation toxicity) 시험법에 따라 수행하였다. 본 연구를 위하여 6주령의 랫드(Rat)를 도입하여 1주간 순화시킨 후 암수 각각 대조군 5마리, 저농도군(284 ppm) 5마리, 중농도군(1,135 ppm) 5마리, 고농도군(4,540 ppm) 5마리 등으로 군을 구성하여 일일 6시간, 주 5일, 4주 동안 시험물질을 랫드에 전신으로 노출시켰다. 시험물질 노출을 종료하고 2주 후 시험동물을 희생하여 시험물질에 의한 시험동물의 영향을 평가하였다. 사료섭취량 변화, 체중 변화, 임상관찰, 혈액검사, 부검 소견, 장기무게 측정, 조직병리검사 등 모든 시험결과에서 시험물질에 의한 영향은 나타나지 않아 3-methylpentane의 무유해영향농도는 암수 모두 4,540 ppm이상으로 판단되어 세계조화시스템(GHS) 지침 및 고용노동부고시 제2013-37호(화학물질의 분류 표시 및 물질안전보건에 관한 기준)의 특정표적장기독성(반복노출) 구분 표시 물질에 해당하지 않은 물질로 판단되었다. Objectives : The purpose of this study was to obtain information regarding Globally Harmonized System(GHS) classification and health hazards that may result from a 4 weeks inhalation exposure of 3-Methylpentane in Sprague-Dawley rats. Methods : The testing method was conducted in accordance with OECD guidelines for the testing of chemicals No. 412(Subacute Inhalation Toxicity). The Rats were divided into 4 groups(5 male and 5 female rats in each group) and exposed to 0 ppm, 284 ppm, 1,135 ppm, 4,540 ppm 3-Methylpentane in each exposure chamber for 6 h/day, 5 days/week, for 4 weeks. After two weeks, the test animals were autopsied and carried out blood test and biochemical tests and histopathological examination. We used PRISTIMA (Toxicology data management system) to confirm the system and to have confidence of the raw data. Results : No death and particular clinical presentation including weight change and change of feed rate was observed. Relationship between dose, gender and response was also not significantly changed in hematologic examination, biochemical examination of blood and blood coagulation time. The histopathologic lesions caused by the test substance did not appear. Conclusions : NOAEL(No Observable Adverse Effect Level) of 3-Methylpentane is more than 4,540 ppm in male group and female group and the Ministry of Employment and Labor Guidance Announcement No. 2013-37(criteria for the classification marks and Safety of Chemicals) Specific target organ toxicity(repeated exposure) was determined with a substance that is not the separator material.