Methodologies for introduction of DNA into cells are essential in molecular genetics and vital for applications such as genetic engineering and gene therapy. The use of cyclodextrins (CyDs) for increased efficiency of introducing DNA into eukaryotic cells (transfection) has been reported, but CyDs' effect on the introduction of DNA into bacterial cells (transformation) is unknown. Here, we have investigated the potential of using CyDs in the transformation of chemically competent in-house, commercially available, and, on non-competent bacterial cells, with plasmid DNA of two different sizes. Possible interactions between CyDs and DNA were studied with nuclear magnetic resonance (NMR) spectroscopy. The presence of CyDs resulted in an up to fourfold increment of the transformation rate for in-house cells, with beta-CyD and derivates giving the strongest effect. For commercial cells and transformation with megaplasmids, a more moderate effect around 1.4-fold was obtained. However, CyDs have little or no effect on DNA uptake by noncompetent cells. Results obtained from NMR spectroscopy show no interactions between CyDs and DNA-like molecules, which indicated that the CyDs' effect is related to the bacterial cell wall.