We have investigated the dynamical state of the disks of a set of 9 spiral galaxies fainter than MB = −18 and with Hubble types Scd or later for which rotation curves are available in the literature. The rotation curve of each galaxy is decomposed in disk and dark halo contributions in order to determine the mass distributions of both components. The velocity dispersion of dwarf spirals is not known, but we use the vertical scale heights of the disks assuming vertical hydrostatic equilibrium to derive estimates of the velocity dispersions. For this purpose we have performed a statistical flattening analysis of faint dwarf spirals in the ESO-Uppsala catalogue. We find that the intrinsic ratio of vertical to radial scalelengths of these types of galaxies is z0/h = 0.2 corresponding to an intrinsic flattening of q0 = 0.14.