In vitro techniques are require to better understand coelomocytes - mediated immune responsed. The main obstacle in the long-term cultures of coelomocytes is the contamination with bacteria and fungi from earthworms exterior and coelomic cavity. To avoid this, coelomocytes are retrieved through a small incision in the body wall from earthworms maintained at 10°C for at least 2 weeks. Culture medium is supplemented with 1% streptomycin/penicylin (Sigma) and 0.001% thiomersal (Merck). Freshly retrieved coelomocytes of Dendrobaena veneta contain granular and non-granular cells in the proportion close to 1 : 1 while in our four-month in vitro culture granular cells predominate.