Neutral hydrogen observations with the 100-m Effelsberg radio telescope are presented for 268 spiral galaxies from the Revised Flat Galaxy Catalog (<VII/219>). Fluxes, radial velocities and line widths are given for 121 detected galaxies, as well as search parameters for 147 undetected objects. Most of the detected galaxies are late type (Sbc -- Sdm) spirals with a mean M_25_/L_B ratio of 2.5 in solar units. (M_25_ is the total mass within the 25mag/arcsec^2^ isophote) and a mean hydrogen mass fraction M_HI_/M_25_=0.13. Correlations between global parameters are discussed briefly. A comparison with a sample of nearby galaxies (within 10Mpc) demonstrates the validity of the same linear relation between the optical luminosity (L_B_) and the linear diameter (A_25_) down to the smallest galaxies.