—The operational safety of an organisation is significantly influenced by the substitution system, it means that in case of absence of employees they are substituted by professionally competent persons. Substitution system need to have sufficient tolerant ability i.e. robustness to be able to maintain the operation safety of the organisation in case of absence. One of the factors that determine robustness of the substitution system is to what extents of differences are between professional competences of the substituted person and the substitutive person. The focus of my research was to discover anomalies of the substitution network of a middle-sized company using network theory methods. During the research I mapped four different ways the substitution network of the organisation and I investigated the differences and sameness of the particular networks. The differences and sameness that were discovered during the analysis show those latent anomalies of the substitution network, whic...