Depression is highly prevalent in patients with advanced cancer, commonly affecting quality of life. Considering the response delay with conventional antidepressants and the short life expectancy for these patients, treatments for Major Depressive Disorder (MDD) with faster onset of action are desirable. In this case report, a female patient with metastatic ovarian cancer presented rapid and sustained response to intramuscular (IM) injections of ketamine (1mg/kg). Over a course of six treatments, her mood response was identical on each occasion and provided remission of her depressive symptoms. Pain was also improved, although for a shorter duration. These findings support the use of IM ketamine as a possible antidepressant option for this population.