Selected aspects of digestion in captive giraffes were investigated in two trials with a type of marker that is new for digestive studies in non-domestic species. n-Alkanes were used as internal and external markers. In Trial 1, diet composition, intake, and digestibility were directly measured and estimated with the marker. Six giraffes were dosed once daily for 3 weeks with labeled pellets containing 3,800 ppm of each C28, C32, and C36 alkanes at ~100 mg/100 kg bodyweight. Intake of cabbage, browse, and a cattle pellet could accurately be estimated with the alkane method. For an oat/wheat mix and clover hay, however, there were large differences between directly measured intakes and those obtained using the alkane method, with the alkane method substantially underestimating. In Trial 2 mean retention times (MRTs) of fluid and particle phase were estimated. Three subadult giraffes were dosed once with cobalt-ethylenediamine tetraacetic acid (Co-EDTA) (260 mg) and alkanes C29 (140 mg) and C36 (370 mg). The average MRT for the fluid phase (Co-EDTA) was 31 hr and for the particle phase (alkanes) was 41 hr (C36) and 43 h (C29 ). This study showed that n-alkanes have potential as markers for investigating digestive strategies in non-domestic herbivores.