AbstractRelationships between urinary levels of α1‐microglobulin (α1M) and ulinastatin (UT) in patients with dementia were investigated. There were no significant differences in α1M and UT levels and α1M: UT ratios among three groups: age‐matched control subjects, patients with either Alzheimer‐type senile dementia (ATD) or vascular dementia (VD). Although a positive correlation was established between α1M and UT levels in these groups, the regression of the demented patients differed significantly from that of controls (P<0.05). A tendency towards a negative correlation between α1M: UT ratios and the levels of severity or duration of the disease was displayed in the ATD group, whereas a tendency toward a positive correlation between α1M: UT ratios and the levels of severity was observed in the VD group. These results suggest that changes in the relationships between urinary levels of α1M and UT may provide a useful biochemical index for diagnoses