The morphology of complexes between DNA and the inorganic salts calcium phosphate and aluminum hydroxide, which function as DNA carriers, was examined. Calcium phosphate is a conventional DNA carrier for anchored cells and is known to condense and precipitate DNA molecules. At higher concentrations of DNA, the size of the DNA-calcium phosphate complex increased. However, mono-dispersed and condensed particles were more prevalent at increasing concentrations of DNA. DNA uptake was more efficient in the particles compared to the aggregates. We also investigated the complex between DNA and aluminum hydroxide, which already used as an adjuvant. The extent of DNA uptake was also affected by the size of the DNA-aluminum hydroxide complex. The dramatic changes in DNA conformation are discussed in relation to the efficiency of gene transfection.