The angular distributions of photons scattered by human breast tissues (adipose and glandular) and by eight breast-equivalent materials (water, polymethylmethacrylate, nylon, polyethylene and four commercial breast-equivalent materials simulating different glandular-adipose proportions) have been measured at a photon energy of 17.44 keV (Kalpha-radiation of Mo). Transmission target geometry has been used with an acceptance of +/- 0.6 degrees and an uncertainty of approximately 7%. Experimental molecular form factors were extracted from diffraction patterns normalizing the number of scattered photons with theoretical data in regions where no structure is expected. Linear attenuation coefficients have been measured for all samples at this energy. The results for water, polymethylmethacrylate, nylon and adipose tissue agree with former reported data. The results for human breast tissues at low and medium scattering angle (1-25 degrees, corresponding to the momentum transfer region between 0.2 and 3 nm(-1)) differ from the breast-equivalent materials. The results for adipose tissue are similar to the corresponding values from commercial breast-equivalent materials while the results for glandular tissue are similar to those for water.