Molecular imaging has become a hot research area since the early of this century. It utilizes the molecular interaction between the imaging probes and the particular targets to image the change of the area of interest. Molecular imaging opens up the possibility of early diagnosis as well as monitoring treatment response and outcomes that tailors individualized therapies. Researches have been focused on the development of imaging probes for various imaging modalities. Thanks to the contribution of chemistry and material sciences, certain probes have been endowed with multifunctions that enable multimodal imaging or combinatorial diagnosis and therapeutics termed as theranostics. In this special column, five review articles and three research reports have been selected to illustrate the principles of design and biomedical applications of the molecular imaging probes for fluorescence imaging, Raman spectroscopic imaging, X-ray computed tomography (CT), magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT) as well as their combinations.