We describe a new chiral tubule-forming lipid in which the C-O-P headgroup/glycerol backbone Linkage of the archetypal tubule-forming phospholipid, 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine, DC(8,9)PC, is replaced by a C-C-P linkage. Tubule formation from this phosphonate analogue occurs under the same mild conditions as with DC(8,9)PC and produces identical yields, but the phosphonate tubules have cylindrical diameters twice that of DC(8,9)PC tubules. Small-angle X-ray scattering, atomic-force, and optical microscopy reveal the new tubules to consist of fewer coaxially nested cylindrical lamellae than DC(8,9)PC tubules; accordingly, the phosphonate tubules are more fragile. In addition, a small portion of the phosphonate precipitate is in the form of stable open helices, and enantiomerically pure preparations of the new molecule contain significant numbers of helices possessing the unexpected sense of handedness.