The effect of injection of a cholecystokinetic agent, Ceruletide, was compared with that of the fatty meal following a single dose of Biloptin, and Biloptin with Solubiloptin, in regard to efficiency of gall-bladder contraction, cystic and common bile duct visualisation and side effects. In terms of gall-bladder contraction and ductal delineation no advantage was found from giving Ceruletide or Solubiloptin. Gall-bladder contraction occurred more quickly after Ceruletide than after a fatty meal, with corresponding earlier duct delineation, although the gall bladder was completely emptied of contrast medium in a significant proportion of Ceruletide cases. The incidence of abdominal pain was significantly greater after Ceruletide than after a fatty meal. Because Ceruletide requires an intramuscular injection and has no significant advantage over the fatty meal in regard to gall-bladder contraction and ductal delineation, its use in cholecystography is unjustified. A morning dose of Solubiloptin following Biloptin the previous evening offers no advantage over the Biloptin and fatty meal regimen.