Minimal Deviation Hepatoma 7288 C cells were cultured in confluent layer with labeled linoleic, alpha-linolenic, eicosa-8,11,14-trienoic and stearic acids. The cells in culture preserved their ability to convert stearic acid to oleic acid. They also synthesized arachidonic acid from linoleic acid or eicosa-8,11,14-trienoic acid. The conversion was very low with linoleic acid and high with eicosatrienoic acid. Eicosapentaenoic acid and other homologs of the alpha-linolenic acid family were synthesized from alpha-linolenic acid. The biosynthetic patterns were the cells was modified by the fatty acid composition of the media.