Using small-angle neutron scattering (SANS), we have measured the salt-dependent static structure factor of di- and trinucleosomes from chicken erythrocytes and from COS-7 cells. We also determined the sedimentation coefficients of these dinucleosomes and dinucleosomes reconstituted on a 416-bp DNA containing two nucleosome positioning sequences of the 5S rDNA of Lytechinus variegatus at low and high salt concentrations. The internucleosomal distance d was calculated by simulation as well as Fourier back-transformation of the SANS curves and by hydrodynamic simulation of sedimentation coefficients. Nucleosome dimers from chicken erythrocyte chromatin show a decrease in d from ∼220Å at 5mM NaCl to 150Å at 100mM NaCl. For dinucleosomes from COS-7 chromatin, d decreases from 180Å at 5mM to 140Å at 100mM NaCl concentration. Our measurements on trinucleosomes are compatible with a compaction through two different mechanisms, depending on the salt concentration. Between 0 and 20mM NaCl, the internucleosomal distance between adjacent nucleosomes remains constant, whereas the angle of the DNA strands entering and leaving the central nucleosome decreases. Above 20mM NaCl, the adjacent nucleosomes approach each other, similar to the compaction of dinucleosomes. The internucleosomal distance of 140–150Å at 100mM NaCl is in agreement with distances measured by scanning force microscopy and electron microscopy on long chromatin filaments.