The incorporation of the fluorescent probe 3,3-dialkyloxacarbocyanine bromide H-510 (where alkyl is ethyl- (C2), nonyl- (C9), or octadecyl (C18) groups) into cells of different kind has been explored. It has been revealed that the length of alkyl chains significantly influences the dynamics and mechanisms of accumulation of the probe by the cells. It has been found by microfluorimetry that all probe species have similar spectral characteristics in bone marrow cells, indicating that all probes, independently on their lipophilic properties, are incorporated into micelle-like structures formed probably by cell phospholipids. Spectroscopy experiments have shown that, in hepatocytes, the fluorescent probes 3,3-diethyloxacarbocyanine bromide (H-510/C2) and 3,3-dinonyloxacarbocyanine bromide (H-510/C9) are mainly accumulated in weakly polar media (nonpolar and weakly polar lipids of these cells). The luminescence maximum of the H-510/C18 probe in hepatocytes is blue-shifted and coincides with that in an albumin solution. We suppose that the incorporation of the probe into cells occurs by endocytosis when the probe binds to surface proteins.