Ferroelectric nanotubes have potential application in inkjet printing and drug delivery due to their piezoelectric property and unique geometry. For different applications, different electrical boundary conditions are applied to ferroelectric nanotubes. In the present work, domain structures in ferroelectric nanotubes (FNTs) under different electrical boundary conditions are predicted through a phase field model. Simulation results show that domain structures are highly dependent on the compensation of polarization-induced surface charges. In order to reduce the depolarization energy, polarizations in FNTs form a vortex structure under an open-circuit boundary condition. When surface charges are compensated on the inner and outer surfaces, a multi-domain structure is formed in FNTs as a result of competition between the long-range electrostatic and elastic interactions. However, a single-domain structure is energically favourable in FNTs if the upper and lower surfaces are short-circuited. DOI: 10.1063/1.2966366 Applied Physics Letters 93, 042906 (2008)