This protocol describes two biological assays to evaluate pathogenicity of Burkholderia cepacia complex (Bcc) strains against the nematode Caenorhabditis elegans. Specifically, these two assays allow one to identify if the under-investigated Bcc strains are able to kill the nematodes by intestinal colonization (slow killing assay, SKA) or by toxins production (fast killing assay, FKA). The principal differences between the two assays rely on the different killing kinetics for worms.