A cultivation method has been developed for the boreal deep-water sponge Geodia barretti (Demospongiae, Geodiidae), a species which is common in the deep Norwegian fjords. The species is known to contain secondary metabolites which are biologically active. Choanosomal fragments of 2-4 cm(3) (approximately 3-7 g) were kept in half-open systems. Cicatrisation and regeneration processes were surveyed by histological examination during 8 months of cultivation. During the first weeks, the weight of the fragments decreased. However, after about 6 weeks the weight equalled the original weight, and after 1 year the weight had increased by about 40% compared to the original weight. The initial decrease was due to complex healing processes and the regeneration of the cortex, a sterrastral layer typical for the family of the Geodiidae. We document, for the first time, the complete cortex reconstruction in an adult G. barretti, as well as the development of egg cells during cultivation. Our study represents the first attempt at biotechnological production of boreal sponge tissue. For successful farming of G. barretti and other boreal and arctic sponges, however, further investigation is needed on factors stimulating growth and secondary metabolite production in the target species.