Introduction This pamphlet discusses@ in general terms@ the causes and particularly the prevention of skin disorders (dermatoses) which may result from long exposure to petroleum oils. Discussion will center principally on petroleum cutting oils and emulsions since it is more likely that they will be in direct contact with operating personnel for extended periods than other petroleum products. The history of the dermatoses associated with petroleum oils and emulsions antedates the development of modern specialized cutting oils@ emulsions and lubricants by several decades. The earliest reference to oil dermatoses mentions@ chiefly@ skin lesions of spinners and machinists exposed to sperm and shale lubricating oils. The first published report of oil acne appeared in 1861. Since then@ and closely identified with the rapid technological advances of modern industry@ considerable literature on the subject has been accumulated. The first and most important step in planning a program for combating dermatoses is to acquire knowledge of the factors effecting their occurrence. A program of this nature@ suitably organized and administered@ is capable of achieving considerable success in reducing the incidence of skin disease.