Comprehension of biological processes in cells, tissues and organisms requires identification and analysis of numerous biological objects, mechanisms of their action and regulation. Microarray (biochips) technology is a rare tool to solve this problem. It is based on high-throughput recognition of a target to the probe and has the potential to measure simultaneously the presence of numerous molecules in multiplexed testes, all contained in a small drop of test fluid. Biochips allow the parallel analysis of genomic or proteomic content in healthy versus disease-affected or altered tissues or cells. The signals read-out from the biochips is done with organic dyes which often suffer from photobleaching, low brightness and background fluorescence. Recent data show that the use of fluorescent nanocrystals "quantum dots" (QDs) allows push away these restrictions. The QDs are sufficiently bright to be detected as individual particles, extremely resistant to photobleaching and provide unique possibilities for multiplexing thus supplying the microarray technology with the novel read-out option enabling the sensitivity of detection reaching the single molecule level. This paper is aimed at the development of the approaches to the QDs application in microarray-based detection. Possibilities of QDs application both in solid state (planar) biochips as well as intensively developing technique of suspension biochips (bead-based assays or liquid biochips) are demonstrated. The latter are more and more applied for simultaneous identification of very large numbers of molecules in proteomics, genomics, drug screening and clinical diagnostics. This assays base on spectral encoded elements (as a rule polymer microbeads). The benefits of using optically encoded microbeads (instead of the solid-state two-dimensional arrays) are derived from the freedom of bead to move in three dimensions. Polymeric beads optically encoded with organic dyes allow for a limited number of unique codes, whereas the use of semiconductor nanocrystals as fluorescent tags improves the beads multiplexed imaging capabilities, photostability and sensitivity of the biological objects detection. Additionally, an employment in suspension biochips of Frster resonance energy transfer (FRET) allows improving detection specificity. The absence of fluorescent background from non-interacting with the beads dye-labelled antibodies additionally increases the sensitivity of detection and further facilitates the multiplexing capabilities of nanocrystals-based detection and diagnostics. So the combination of the biochips and QDs techniques allow increasing detection sensitivity and significantly raising the number of detected objects (multiplexing capacities). Such combination should provide the breakthrough in proteomics, particularly in new drugs development, clinical diagnostics, new disease markers identification, better understanding of intracellular mechanisms.