ABSTRACT. – Macroscopic investigations on the capability of Sepia officinalis to regenerate lost tentacles reveal a process of renewal that can be divided into six stages of differentiation, corresponding to the studies on arm regeneration in the cuttlefish by Féral (1977, 1978): the protrusion of the central main nerve cord, the scarring of the wounded tissues, the formation of a hemispherical bud which is developing into a cone-like shape, the sucker-formation, and finally the recovery of the functional ability. Following Féral (1979) we applied a three-phase model based on histological-cytological aspects to evaluate degeneration, dedifferentiation, and re-differentiation processes of the wounded tissues in the regenerates. After amputation an intensive migration of amoebocytes into the wounded tissues begins, which is followed by the disintegration of cells at the wound surface. Inside the wound an autolysis of amoebocytes into a plasmoidal mass occurs and forms the primary wound occlusion which is replaced by a monolayered epithelium. The total differentiation of all tissues occurs in the latest phase starting in the central main nerve cord and proceeding to the peripheral regions of the tentacle. The sucker primordia become innervated only towards the end of the third month. Their regeneration is compared with sucker differentiation during embryonic development.