Abstract: ImmunoPET imaging has become a widely employed technique for the diagnosis, staging, and prognostic evaluation of malignant tumors, playing a crucial role in target visualization and pharmacokinetic studies. However, the clinical application of intact monoclonal antibodie (mAb) for immunoPET imaging is hindered by issues such as slow pharmacokinetics and prolonged blood circulation times. Fragment antigen binding (Fab) and fragment antigen binding dimer (F(ab')₂), derived from mAb, offer significant advantages, including enhanced tissue penetration and rapid blood clearance, while retaining the ability to specifically bind antigens. These properties make them particularly suitable for same-day imaging, positioning them as key areas of focus in the field of immunoPET. The authors highlight the advancements in the use of Fab and F(ab')₂ for targeted cancer immunoPET imaging, and explores their potential for further development, along with the challenges that remain.