SDHD, which stands for succinate dehydrogenase complex subunit D, is one of the two transmembrane subunits of the four-subunit succinate dehydrogenase protein complex that resides in the inner mitochondrial membrane. It also refers to the gene that codes for this protein.

Germline mutations in SDHD were first linked to hereditary paraganglioma in 2000. Since then, it has been shown that mutations in SDHB and to a lesser degree SDHC can cause paranglioma as well familial pheochromocytoma. Notably, the tumor spectrum is different for the different mutations. SDHB mutations often lead to metastatic disease that is extra-adrenal, while SDHD mutation related tumors are more typically benign, originating in the head and neck.