We present high spatial resolution Hα rotation curves of late-type dwarf and LSB galaxies. From our analysis we find good agreement between our Hα data and the HI observations taken from the literature, concluding that the HI rotation curves for these galaxies suffer very little from beam smearing. A preliminary analysis of our data rules out the CDM model in the inner regions of these galaxies. ; Comment: Contribution to "Tracing Cosmic Evolution with Galaxy Clusters" (Sesto 2001), ASP Conference Series