BACKGROUND: The study of magnetic nanoparticles (MNPs) for drug delivery has recently seen a surge of interest even though the first studies were conducted as early as in the seventies. Despite this, there are still gaps in the knowledge of the field, implicating the complexities in designing the ideal MNP for drug delivery. The large surface area of MNPs and the ability to manipulate with an externally applied magnetic field render the MNP a good candidate for targeted delivery of drugs. Drugs are conjugated to the surface of MNPs or encapsulated within, while the surface of MNPs receives a protective coating and is functionalised with ligands, enzymes, linkers, and active molecules to deliver the drug to a targeted site. RESULTS: These MNPs in the form of nanogels, micelles, polymers, dendrimers, and receptor-targeted have been studied in vitro and in vivo to assess morphology, cytotoxicity, localisation and others, which are the indicators of efficacy. While preclinical studies appear to be promising, there is a limited translation from bench to bedside for reasons such as inconsistent results between similar studies and inadequate profiles of toxicity, drug release and biodistribution amongst many others. However, the substantial number of clinical trials of MNPs in other applications such as hyperthermia for the treatment of cancer and imaging shows that there is indeed potential in the development of MNPs to achieve successful drug delivery. CONCLUSION: The lack of optimal design for MNP surface functionalization and conjugation to drug and other molecules for delivery to target cells gives plenty of room for the research and development of the ideal MNP, which is indicated for the future of MNPs in biomedical applications.