In recent years there has been an increase in interest in the use of colloidal quantum dots (QDs) in biology and medicine. In particular, QDs can be a perspective nanoscale object for theranostics, in which due to the specific accumulation of drug-loaded QDs in the pathological focus, its simultaneous visualization and targeted therapeutic influence occur. One of the serious limitations of the use of QDs in medicine is their potential toxicity, especially when the nanocrystal material contains elements such as cadmium or plumbum. Therefore, it is promising to develop labels based on QDs of relatively less toxic semiconductors of group I-III-VI, such as CuInS₂ and AgInS₂. In this study, biodistribution and biocompatibility of QDs based on the AgInS₂ compound with a ZnS shell (ZAIS) are considered. In the study of biodistribution, the accumulation of QDs in organs such as liver, lungs, heart and kidneys was revealed. It was shown that QDs in the dose range from 2 • 10^–7 to 4 • 10^–6 M/L at intravenous administration in rats does not have a significant effect on body mass dynamics and basic hematological parameters for 30 days. Thus, ZAIS QDs can be used to visualize tissues and organs in various pathological processes, and immobilization of the drugs on their surface will allow to approach their application for theranostics.