The best-known (fibrillar) collagens support cellular adhesion primarily through a subset of collagen-binding integrins, α1β1, α2β1, α10β1 and α11β1, which have been shown to recognise a series of similar sequences. These contain Gxx'GEx''motifs (where x is a hydrophobic residue, x' is usually O (hydroxyproline) and x'' is often R). Here, we review the variations within such sequences that support integrin reactivity, and their distribution across the 28 human collagens. The main basis for our understanding is the use of triple-helical, homotrimeric collagen peptides, but this work is far from exhaustive, and there is good evidence that heterotrimeric collagens where the sequence of interest occurs in two or even just a single chain may still support integrin binding. The fibrillar collagens I, II and III are rich in GxOGER motifs, whereas GxOGEK is more widely distributed, and less frequent in these three archetypal fibrillar collagens.