Background: Nanobacteria-like structures (NLSs) or calcifying nanoscale particles (CNPs) are novel ambiguous entities. As their names imply, they are tiny creatures (100 to 500 nanometers). Compared to ordinary bacteria, they can exhibit some unbelievable properties such as resistance to conventional antibacterial procedures. Form a scale point of view, these microorganisms are much smaller than ordinary bacteria and are preserved from the outer environment by their rigid apatite shell. The above-mentioned protective properties of nanobacteria are responsible for a dangerous in vivo calcification procedure causing pathological infectious diseases. Objectives:The main goal of this study was to identify and isolate the nanobacteria from patients with atherosclerosis. Methods: Human vascular tissues were assessed for the presence of NLSs in atherosclerotic plaques at Sina Hospital, Tehran, Iran. All 40 samples obtained from patients as the wastes of surgery showed crystallization in vitro after about 10 days. Crystallization was seen also in filtered media. The precipitates of media were investigated by scanning electron microscopy (SEM). Results:NLSs were seen in all samples by SEM. After confirming the NLSs presence, they were characterized by TEM, XRD, and SEM/EDAX. Conclusions:The NLSs are observed in patients with atherosclerosis.