The invention relates to the use of known and novel phenalkyl carboxamide derivatives of the formula (I) wherein the structural elements have the meaning as indicated in the description, for the control of nematodes and/or other helminths, particularly in agriculture and in the animal health field, formulations containing such compounds, particularly agrochemical formulations, and methods for the control of nematodes and helminths. The invention further relates to novel phenalkyl carboxamide derivatives, processes for their preparation, formulations containing such compounds, methods for the control of nematodes and helminths and their use as pest controlling agents, particularly their use as nematicides and their use as anthelmintics against endoparasites in animals and humans.