Proteomic approaches play an important role in the study of complex biological systems. The application of proteomic technologies in plant science has been strongly supported by the completion of genome sequence projects of the model plants Arabidopsis thaliana and rice. This review focuses on the state of proteomic technologies with special emphasis on their application in plant biology. An overview of recent developments in 2-dimensional gel electrophoresis and liquid chromatography-based multidimensional protein identification technology, MudPIT is provided. These techniques are commonly combined with mass spectrometric methods for identification of proteins. Furthermore, protein expression profiling by antibody arrays and the selection of required recombinant antibodies by phage display are described. Interaction studies, using functional protein microarrays or the yeast two-hybrid system are presented as powerful techniques to gain insights into the function of proteins. Advantages and limitations of the described methods as well as their current and potential future applications in plant research are discussed.