Large, multi-component protein assemblies are involved in many DNA transactions such as recombination, replication, transcription, and repair. In order to progress in the understanding of different key steps of these mechanisms, it is imperative to analyze the structure of the DNA-protein complexes involved and the dynamic interactions that govern their assembly, function and disassembly. These complexes are usually studied in vitro using a combination of biochemical and biophysical methods. The AFM instrument has become indispensable for probing DNA-protein interactions at the single molecule level. This application note only covers a few examples of the knowledge that AFM has brought forth.