In the present work, we show a new approach for decompaction of DNA-cationic surfactant complexes, e.g., lipoplexes, by using beta-cyclodextrin (beta-CD). The DNA decompaction was achieved by dissolving the surfactant aggregates in the complex by making use of the high affinity between the beta-CD and the free surfactant in solution. The results from fluorescence microscopy and adiabatic compressibility measurements indicate that coils and globules do not coexist. The reported procedure using beta-CD is an efficient way to decompact DNA surfactant complexes because the association constant of surfactants with beta-CD is large. The surfactant's interaction with beta-CD is specific and the nonspecific interaction between beta-CD and biological interfaces is small.