The influences of sex and acute inflammation on prostaglandin biosynthesis in rabbit gallbladder were examined by radiochromatography. Male rabbit gallbladder microsomes converted small amounts of labelled arachidonate to total prostaglandin synthesis with PGE2, 6-keto PGF1 alpha (stable metabolite of PGI2) and PGF2 alpha as the major products synthesized. Microsomes from the male rabbit gallbladder inflamed by bile duct ligation for 3 days increased total prostaglandin synthesis five-fold with 6-keto PGF1 alpha being the major prostaglandin produced. Female rabbit gallbladder microsomes converted three times more arachidonate to total prostaglandin synthesis than did microsomes from the male rabbit. Bile duct ligation did not alter total prostaglandin biosynthesis in the female rabbit gallbladder, but significantly decreased synthesis of PGE2, thromboxane B2 and PGF2 alpha and increased synthesis of 6-keto PGF1 alpha. These data suggest that although bile duct ligation had different effects on male and female gallbladder total prostaglandin synthesis, 6-keto PGF1 alpha is the major product induced by this stimulus for acute inflammation.