In nuclear medicine, the detection of inflamed and infected lesions is of growing interest. Extensive efforts have been made to develop radiopharmaceuticals specific for inflammation or for discriminating sterile inflammation from infection. 99mTc is the worldwide most widely used radioisotope for SPECT imaging. The scope of this review article is to give an overview on the development of 99mTc-labelled small molecule radiotracers targeting inflammatory lesions and infections, ranging from their radiopharmacological evaluation to examples of their clinical applications. A systematic overview of 99mTc-citrate, 99mTc-antibiotics and antifungal agents as well as 99mTc-labelled antimicrobial peptides is provided. Additionally, the class of 99mTc-labelled cyclooxygenase-2 inhibitors is discussed, since cyclooxygenases are known to play a key role in inflammatory diseases and also in malignant neoplastic diseases. In a short perspective, newer developments in the field of inflammation imaging covering 99mTc-labelled bacteriophages and chemotactic peptides are highlighted.