Candida bombicola (ATCC 22214) and C. apicola (ATCC 96134), grown on glucose (100 g l(-)1) and arachidonic acid (5Z, 8Z, 11Z, 14Z-eicosatetraenoic acid; AA), 1.25 g l(-1), synthesized sophorolipid up to 0.93 g l(-)1. Acid hydrolysis of sophorolipid yielded 19-hydroxy-5Z, 8Z, 11Z, 14Z-eicosatetraenoic acid (19-HETE) and 20-hydroxy-5Z, 8Z, 11Z, 14Z-eicosatetraenoic acid (20-HETE) which were identified by TLC and GC-MS; the ratio of synthesis was 73:27, respectively. Conversion of AA by immobilized Candida bombicola, suspended in beads of 2% (w/v) calcium alginate for 96 h, gave an 83% conversion of 1 g AA l(-1) to 19- and 20-HETE. There was no significant loss in the efficiency of the immobilized cells after ten uses.