Phage display procedure was applied to the N-terminal domain of human topoisomerase I. The consensus sequence identified for clones binding to the N-terminal domain was found in 35 human proteins that are either permanently or temporarily located in the nucleus. They are in majority involved in the DNA repair, transcription, RNA metabolism or cell cycle control. Four of identified proteins: Bub3 protein, Cockayne syndrome protein A, damaged DNA binding protein 2 and GRWD protein belong to WD-repeat proteins and their sequences recognized by the N-terminal domain are identically localized.