Several indices used as indicators of fluctuating asymmetry and the statistical analysis of the variation in asymmetry are summarised. The results obtained in different breeds of chickens for the fluctuating asymmetry of morphological and secondary sexual traits are shown, besides with the relationship between fluctuating asymmetry and two measures of stress: heterophil to lymphocyte ratio and tonic immobility duration. Any two or all three types of bilateral asymmetry (fluctuating, directional, and antisymmetry) occurred together for the same trait in the different breeds. The duration of tonic immobility was positively associated with the mean relative asymmetry of all traits in hens from the Villafranquina. Males from this breed had a positive relationship between relative asymmetry for wing bay area and leukocyte ratio. Results suggest that relative asymmetry measures did not provide a general tool to assess stress susceptibility.