Alpha fatty acid derivatives cis-monounsaturated for use as a medicament.

\ The present invention relates to compounds of Formula I: (CH {2}) _ {a} -CH = CH- (CH 2 {}) _ {b} -CH {3} where (a) and (b) can have any value between 0 and 14 and (X) It can be any atom or group of atoms with a weight between 4 and 200 Da; for use as a medicine, particularly in the prevention and / or treatment of diseases whose common etiology is based on structural and / or functional lipids located in the cell membrane; except using the compounds of Formula I wherein (X) by OH, NH 2} {3} {CH or for the prevention and treatment of cardiovascular diseases and obesity, or for the treatment of cancer is replaced.