The anaerobic protozoan parasite Entamoeba histolytica has mitosomes that are mitochondria lacking some canonical functions and organelle DNA. Mitosomes play an important role in the life cycle of the parasite. The distribution of proteins in mitosomes is not uniform, and how mitosomes are maintained and retained is unknown. To answer these questions, we developed a transplant method for mitosomes with hemagglutinin-tagged protein into recipient cells containing mitosomes with Myc-tagged protein. Immunofluorescence staining showed that the two protein tags colocalized in single mitosomes in some recipient cells. These results suggest that our transplant method can be used in anaerobic protozoa and that donor mitosomes may obtain recipient proteins through fusion with other mitosomes or through de novo synthesis of proteins in recipient cells.