Whereas α-helix has an almost unique secondary structure, β-structure or conformation appears in various structural motifs. Basically, β-structure is either in parallel or anti-parallel β-sheet, but recent structure determination of phage and viral structural proteins revealed a variety of new structure motifs such as β-helix, β-spiral, and β-propeller in addition to traditional parallel and anti-parallel β-sheet, β-barrel or β-sandwich. This article will review these new β-structure motifs and their functional implications.