Abstract: The influence of the sanitary status of the trees on the macroscopic and microscopicstructure of the cork was studied in two Algerian zones of cork production: coastal (M’Sila) andmountainous (Zarieffet). Cork samplings were performed on 43 healthy trees (foliar deficit<25%) and 19 declining trees (foliar deficit >60%). The macroscopic study showed that corkgrowth varies in relation to the ecological zone of origin. In mountain, the cork of the healthytrees, that grows slowly, has more small sized pores (section <1mm) than that of the coastlinewhich possesses 45% of large pores (section >2mm). In the cork of the declining trees, theslowing down of the growth induced an increasing number of small pores. The microscopicstructure of the cork also proved to be linked with the growth speed. On healthy trees, the size ofthe cork cells (H/L index) reached 1.41 in the littoral, versus 1.09 in the mountain. On the otherhand, the cell wall thickness is inversely correlated to cell size. The structure of the cork generallydetermines its quality. Healthy cork-oaks from mountain produced better cork (less flexible) thanthose from the littoral.