Background: Cancer can have a deleterious impact on the well-being of a patient and can affect the mental health. Cancer treatment is influenced by anxiety and depression and thereby recovery, quality of life, and survival may get hampered. Depression is the most common psychiatric syndrome that has received the most attention in individuals with cancer. It has an intense impact on lives of patients and it continues to be underdiagnosed and inadequately treated. Depression most commonly coexists with other syndromes such as panic disorder, generalized anxiety disorder, and post-traumatic stress disorder. Cancer is threatening and understandably many patients get anxious in response to that threat and anxiety appears to increase as the illness progresses. Depression and anxiety have impact on morbidity and mortality leading to worsening of quality of life. In patients with cancer on treatment, there is a greater degree of association between anxiety and depression with worsening of quality of life. In this study, we assessed prevalence of depression, anxiety, and the quality of life in patients undergoing cancer treatment. We tried to find out the correlation between prevalence of depression and anxiety. We also looked at the quality of life in patients undergoing cancer treatment. Materials and methods: Our study was conducted on 50 patients who were undergoing cancer treatment. We used Hamilton depression rating (HAM-D) and Hamilton anxiety rating (HAM-A) scales, respectively, to assess the symptoms of depression and anxiety. The quality of life was assessed using quality of life-10 (QOL-10) questionnaire. Results: In this study among subjects on chemotherapy, 46.7% had mild depression, 30% had moderate depression, 16.7% had severe depression, and 6.7% had very severe depression. Among subjects on radiotherapy, 53.3% had mild depression, 13.3% had moderate depression, 33.3% had severe depression, and 0% had very severe depression. Among subjects on chemotherapy along with radiotherapy, 20% had mild depression, 40% had moderate depression, 40% had severe depression, and 0% had very severe depression. In this study, 60% had mild anxiety, 38% had mild to moderate anxiety, and 2% had moderate to severe anxiety. Among those on chemotherapy, 66.7% had mild anxiety; among those on radiotherapy, 53.3% had mild anxiety; and among those on chemotherapy + radiotherapy, 60% had mild to moderate anxiety. In this study, there was positive correlation between HAM-A and HAM-D scores, that is, with an increase in HAM-A score, there was an increase in HAM-D score and vice versa. Conclusion: In our study, patients with cancer had higher prevalence of anxiety and depression. Anxiety and depression often lead to poor quality of life.