Background: The leukocyte alkaline phosphatase (LAP) is an enzyme, hydrating phosphate ester in leukocyte which were recently reported to have the increased activity in diabetes and diabetic acidosis. Methods: To illustrate the new parameter of long- term control of serum glucose in NIDDM patients, we determined correlation of LAP activity in conjugation with glycosylated hemoglobin (HbAlc) in N1DDM patients. The normal control included 41 subjects (male 22, female 19) and NlDDM patients. The were made of 59 patients (male 33, female 26) for this study. Results: 1) In normal subjects, the mean level of HbAlc was 5. 08+-0,94% and the mean LAP score was 116+-118, respectively. 2) In NIDDM patients, the mean level of HbAlc was 6. 96+-1,66% and the mean LAP seore was 132+-57. 3) The HbAlc level was higher -on NIDDM patients than those of normal jeets (P<0.05). 4) The LAP ware was higher on NIDDM patients than those of normal subjects, but there was not signifi- cantly statistical difference on both groups (p<0.05). 5) Among NIDDM patients there was not significant correlation between HbAlc and LAP (r=0.31, p>0.05). Conclusion: the LAP activlty ead the HbAlc level were not correlated similarly in NID0g patients. Ovr results suggest that LAP score could not be used as a simple new parameter for NIDDM patients. Therefore the pathophysioiogic mechanism of the LAP score as parameter of diabetes mellitus needs further investigation.