Seasonal changes of the total body length are analysed in six species of Black Sea pelagic Copepods: Acartia clausi Giesbr., Paracalanus parvus (Claus), Oithona nana Giesbr. (syn. O. minuta Kritczagin), Oithona similis Claus, Pseudocalanus elongatus (Boeck), Centropages kroyeri var. pontiea Karav. A reverse correlation is found to exist between the average body length of Copepods and water temperature in the period of their individual development.