The activities of aspartate aminotransferase and alanine aminotransferase in erythrocytes with and without the addition of pyridoxal phosphate were determined in healthy controls and in Indian women with cancer of the uterine cervix. The percent stimulation of the erythrocyte transferases as a result of the addition of pyridoxal phosphate was negligible in the case of normal subjects (less than 5% stimulation). In the patients with cervical cancer, a 23-35% stimulation was observed, indicating a deficiency of vitamin B6. It is not yet known whether the deficiency is the cause of the disease or due to the tumor.