Abstract
The whole-genome sequences of Mycobacterium chimaera strains 850 and 852, which were isolated from two different water samples obtained from a heater-cooler unit at Siena University Hospital (Italy), were determined by combining Nanopore and Illumina technologies. Genomes of both strains 850 and 852 consist of a circular chromosome and five plasmids, with sizes of 6,275,686 bp and 6,453,144 bp, respectively.