Mutations in AT rich interactive domain 1A (ARID1A) are common in ovarian cancers. A study now shows that HDAC6 activity is required for survival of ovarian cancer cells bearing ARID1A mutations. HDAC6 inhibition selectively promotes apoptosis of ARID1A-inactivated cells, supporting the use of HDAC6 inhibition in the treatment of clear cell ovarian cancer.