Unsaturated fatty acids show different types of  isomerisms. We have already learnt about the.concept of  isomerism  in  the  last unit. You would  realize that fatty acids with same molecular formula, as well as, same number of double bonds may differ in the  location of  double bonds  and exhibit positional  isomerism. Oleic acid  has  15 different positional isomers.  Again,  the orientation  of  the two  hydrogen  atoms attached to the two carbon atoms joined  by  the double bonds may differ (geometric