A sporulation and sterilization procedure was used to establish axenic cultures of sporelings of Gelidium canariensis. Sporangial branchlets excised from the thallus were rinsed in distilled water twice and in 1% sodium hypochlorite (2 min). The branchlets were cultivated overnight in multiwell plates with 0.3 ml of autoclaved seawater to promote spore liberation in 90% of the cultivated branchlets. The branchlets were transferred to an antibiotic solution made of ampicillin, penicillin, rifampicin, nystatin (0.2 mg ml-1 each) and 0.1 g ml-1 of GeO2 in liquid PES for 45 days, during which clusters of spores (85-100 spores) were observed on the surface of the branchlet. After 55 days, they became axenic sporelings with the prostrate and erect system characteristic of Gelidium canariensis. Copyright (C) 1999 Elsevier Science B.V.