Organic solvents are hydrocarbon-based substances that dissolve another substance. Organic solvents are usually lipid soluble, volatile and commonly used for painting, printing, degreasing, cleaning, thinning and extraction. Due to their volatility and lipid solubility, organic solvents are easily absorbed across the alveolar-capillary membrane and through the skin. Because organic solvents are lipophilic, they tend to be distributed to lipid-rich tissue, such as adipose tissue, nervous system and liver. Almost all organic solvent can induce skin diseases such as acute irritant dermatitis and chronic eczema. Some organic solvents are associated with allergic contact dermatitis. General and nonspecific central nervous system depression is another common toxic effect induced by most organic solvents. It shows symptoms which are the same as those from alcohol drinking, and those symptoms are completely resolved by removal from exposure to solvents. Long term and repeated exposures to organic solvents can also lead to chronic adverse neurobehavioral effects. These effects are also called as chronic toxic encephalopathy, chronic solvent intoxication and psycho-organic syndrome, and commonly reported symptoms of them are headache, depression, anxiety, and impairment of recent memory. Organic brain lesions can be found in workers suffering from psycho-organic syndrome, and in this case, there is a possibility of persistent disabilities. Carbon disulfide, n-hexane, and methyl n-butyl ketone are specifically toxic to the peripheral nervous system, and cause a symmetric ascending sensory and motor polyneuropathy. Halogenated hydrocarbons including carbon tetrachloride show toxic effects on the heart, liver, kidney, and blood. Toluene can sensitize the heart to arrhythmogenic effects of epinephrine, so sudden death in young and healthy people can be ensued from glue sniffing. Benzene is able to induce any type of leukemia, especially in victims with benzene-associated aplastic anemia. Exposure to some solvents during pregnancy has potential to induce congenital malformation and spontaneous abortion. In the treatment of diseases by organic solvents, the first step should be removal from exposure to the causative solvent.