International audienceThis work analyzes the variability of the mechanical properties of flax fiber bundles and strands (a strand is the set of the bundles issuing from the same stem). A first remarkable result is that to obtain average values with good precisions about twenty randomly selected strands are sufficient. Moreover a comparative study of the fracture properties of bundles issued from different strands leads to the assumption that each stem is particular with special properties. A more detailed study shows that correlations exist between the sections of the strands and their mechanical properties. These trends are similar to those reported for unit fibers. (c) 2017 The Authors. Published by Elsevier Ltd