BACKGROUND Teeth have always been known as stable tissue that can be preserved both physically and chemically for long periods of time. Blood group substances have been known to be present in both the hard and soft tissues of the teeth. OBJECTIVE This study aimed at detection of ABO blood group substances from soft and hard tissues of teeth and also to evaluate the reliability of teeth stored for a relatively long period as a source of blood group substances by absorption-elution technique with some modifications. RESULTS Blood group obtained from the teeth was compared with those obtained from the blood sample. Pulp showed a very large correlation in both fresh and long-standing teeth though it decreased slightly in the latter. Hard tissue showed a large correlation in both the groups indicating that hard tissue is quite reliable to detect blood group and that there is no much difference in the reliability in both the groups. However, combining pulp and hard tissue, correlation is moderate. Correlation of blood grouping with the age, sex, and jaw distribution was carried out. CONCLUSIONS Blood group identification from hard and soft tissues of teeth aids in the identification of an individual.