Objectives : This study was performed to evaluate the salivary secretion, salivary pH and cariogenic activity using unstimulated whole saliva in patients with hematologic malignancy. Methods : Nineteen patients (9 male, 10 female) who had hematologic malignancy and were treated with chemotherapy or bone marrow transplantation, and nineteen normal volunteers (7 male, 12 female) as control group were included. The mean age of patients group and control group was 45.1 and 46.7 years, respectively. Patients group was examined salivary secretion, salivary pH, and cariogenic activity using unstimulated whole saliva and was compared with control group. Results : In comparison with control group, salivary secretion, salivary pH and salivary buffer capacity were significantly lower in patients with hematologic malignancy (p<0.01). Both cariogenic activity(p<0.01) and the number of Lactobacilli(p<0.05) are higher in patients group than control group. Conclusions : These results suggest that the unstimulated whole salivary secretion, pH and buffer capacity were lower in patients with hematologic malignancy than control group. Cariogenic activity is higher in patients with hematologic malignancy than control group. Such salivary factor and cariogenic activity can increase the possibility of induction of dental caries.