Introduction Most of the breakthroughs in the study of viruses have been made when a clearly defined culture system was operating. Cell lines, embryo culture and specific pathogen free (SPF) animals have all been used to aid the understanding of viruses and viro- genesis. At present, these tools are not available within Australia for the study of prawn viruses and only some countries have access to SPF Penaeus stylirostris and Penaeus vannamei. There are no SPF Penaeus monodon despite this being the most frequently cultured prawn species in the world. Recent papers have highlighted the absolute need for cell cultures for expression of prawn viruses [5, 8]. Despite this need existing for 30 years or more, limited progress has been made and no commercial prawn cell lines are available. Due to the viral induced, multibillion dollar losses experienced in prawn aquaculture, there is a continuing interest in prawn cell lines and this has necessitated the reviewing of past experiences to expedite further work. This paper summarises research aimed at producing a continuous cell line, conducted in 1988/89 which, at the time, was considered a failure. However, subsequent published work has, in the main, not advanced much past the point reached by this research. This paper may be of some use to those following this line of work, if only to circumvent some mistakes. Materials and methods Mostly, aquacultured, juvenile Penaeus monodon and rarely, wild caught Penaeus merguiensis and Methods in Cell Science 21: 207–211 (1999).  2000 Kluwer Academic Publishers. Printed in the Netherlands. Early attempts at production of prawn cell lines Leigh Owens & Jan Smith Department of Micribology and Immunology, Australian Institute of Tropical Veterinary & Animal Science, PO James Cook University, QLD 4811, Australia Accepted in revised form 31 August 1999 Abstract. This report describes some unsuccessful attempts to produce continuous cell lines from penaeid prawn tissues in the late 1980s. This infor- mation is presented so that others might save time by not repeating the unsuccessful measures that were attempted. The osmolarity of Penaeus monodon haemolymph was measured at 687 mOsmol/kg (N = 10). Of the media tested, the best medium for cell growth and maintenance was shown to be double strength L-15, supplemented with 10% foetal bovine serum, and 10% prawn muscle extract at 28 °C (~675.5 mOsmol/kg). Prawn muscle extract was made by homogenising 30 g of prawn muscle in 50/50 ratio of distilled water/autoclaved seawater, clarified stepwise by centrifugation at 2k, 14k, 14k ×g for 30 minutes each. The resultant supernatant was heat-inactivated on occasions with no improve- ment in growth. Preconditioned medium, cholesterol, galactose and trehalose supplements and the use of Cell-Tak TM did not improve growth conditions, and haemolymph extracts were detrimental to the cells. In addition it was shown that Nunc TM 25 cm 2 plastic culture flasks were better than Linbro TM and both were better than glass as substrates. The fate of 101 Key words: Cell culture, Prawn tissues individual primary cell cultures, established from penaeid prawns, was as follows. Fifteen of the cultures succumbed to bacterial contamination, five became contaminated with fungi, four with thauas- trochytrids, four succumbed to presumptive viral autocultures and two to ciliate contamination. Cell cultures derived from heart tissue could be main- tained for a mean of 12.7 days (sd 9.7d), those derived from the epidermis 15.6 days (sd 9.0d), ovarian tissue 10 days (sd 2d), lymphoid organ 6.8 days (sd 0.4d), nerve cord and hepatopancreas 2 days. The most persistent cell cultures – those derived from the heart explants – contained dividing cells at 40 days, and epidermis cells were still dividing at 30 days. The longest lasting, non-prolif- erating, but viable, cell cultures were those of subcutis/epidermis and heart cells which remained viable for 240 and 307 days respectively. Only cell cultures from multiple prawns achieved 100% con- fluency in 25 cm 2 plastic culture flasks. No cultures survived attempts at passage by either trypsinisation or mechanical disruption with a rubber policeman. No cell lines were established.