På engelska A method for measuring attenuation coefficients in single-photon emission tomography (SPECT) is described and evaluated, together with a method for attenuation correction using these measured attenuation coefficients. Build-up, caused by scattered photons, is corrected for by a simple substitution in the algorithms. Transmission studies are performed with a 99mTc- or 57Co flood source, and emission phantom studies with 99mTc line sources. The method is evaluated with variable but well-defined phantoms. The result is accurate attenuation coefficients for different densities, dimensions and geometries, and an accuracy of corrected emission activities of better than +/- 10% in most cases. The present limitations of the method for attenuation correction are discussed.