TRF1, a key player in regulation of the telomere length, is a double-stranded telomeric DNA binding factor in vertebrate. The DNA-binding domain of TRF1 shows a sequence similarity to each of the tandem repeat in the DNA-binding domain of the c-Myb protein. Here, the solution structure of the DNA-binding domain of human TRF1 has been determined by NMR. It consists of three helices, and its topological arrangement is very close to that of each c-Myb repeat and also to that of each subdomain of the DNA-binding domain in yeast telomeric protein, Rap1p. The interaction with DNA has been investigated by chemical shift perturbations. The result suggests that TRF1 recognizes the sequence centered on AGGGTTA mainly with its N-terminal arm, N-terminal portion of second helix and both ends of third helix.