Nanomedicine, a term coined by the American engineer Eric Drexler (1955) and Robert Freitas Jr. (1952) in the nineties, can be defined as a complex, multi-disciplinary branch of medicine, in which nano-technologies, molecular biotechnologies, and other nano-sciences are applied at every step of disease management, from diagnosis (nano-diagnostics) to treatment (nano-therapeutics), prognosis, and monitoring of biological parameters and biomarkers. Nanomedicine is a relatively young discipline, which is increasingly and exponentially growing, characterized by emerging ethical issues and implications. Nanomedicine has branched out in hundreds of different sub-fields. A bibliometrics-based analysis was applied mining the entire content of PubMed/MEDLINE, using "nanomedicine" as a Medical Subject Heading (MeSH) search term. A sample of 6696 articles were extracted from PubMed/MEDLINE and analyzed. Articles had been published in the period from 2003 to 2019, showing an increasing trend throughout the time. Six thematic clusters emerged (first cluster: molecular methods; second cluster: molecular biology and nano-characterization; third cluster: nano-diagnostics and nano-theranostics; fourth cluster: clinical applications, in the sub-fields of nano-oncology, nano-immunology and nano-vaccinology; fifth cluster: clinical applications, in the sub-fields of nano-oncology and nano-infectiology; and sixth cluster: nanodrugs). The countries with the highest percentages of articles in the field of nanomedicine were the North America (38.3%) and Europe (35.1%). The present study showed that there is an increasing trend in publishing and performing research in the super-specialty of nanomedicine. Most productive countries were the USA and European countries, with China as an emerging region. Hot topics in the last years were nano-diagnostics and nano-theranostics and clinical applications in the sub-fields of nano-oncology and nano-infectiology.