Feed transit time is the amount of time feed components are retained in the gastrointestinal tract and is often measured by giving a known amount of marker-containing diet and determining the first appearance of the marker in the faeces. Most markers used in digestibility studies are insoluble substances such as Cr203 and acid-insoluble ash which must be incorporated into the diets in substantial quantities for sufficient accuracy in subsequent determinations. Feeding birds a marker-containing diet in a given amount of time is difficult and inaccurate, and force-feeding birds using the Sibbald technique is tedious and not suitable for young broilers. The current paper describes a new fat-soluble marker, a long-chain alkane (C36H74), which can be easily and accurately administered to chickens orally.