Bacterial species capable of causing spoilage of biocide-treated and untreatedbleached flax roves were present in gutters, troughs and splash boards of spinning frames and also in the atmosphere around these frames. The common bacterial isolates can stain the bleached-rove treated with a sub-lethal concentration of a range of biocides or they can also reduce strength of the untreated-bleached-roves by degrading the residual non-cellulosic polysaccharides present on the fibre. However, the bacterial isolates did not cause staining on non-biocidetreated roves. The seven main bacteria isolated were Bacillus cereus mycoides, B. subtilis, Enterobacter cloacae, Klebsiella oxytoca, Micrococcus sp., Pseudomonasfluorescens and P. putida and all the isolates produced pectate-lyase on both sterilizedbleached fibre and in liquid culture. B. subtilis also produced xylanase on both substrates tested. None of the isolates produced cellulase on either substrate. Infra-red analysis of the stain produced by the bacteria suggested that compounds present were similar to melanin. Of the seven biocides tested (Dodigen {226X}, Durocid VA, AAS, SOPP, Preventol WB, Resista 4102, Rustol HEK and Sandocide), Dodigen (226X), Preventol WB, Resista 4102 and Rustol HEK offered the best protection of roves against bacterial staining.