Accumulation of tau protein is associated with both Alzheimer's disease (AD) and late-life depression (LLD). Alzheimer-associated neuronal thread protein (AD7c-NTP), which is closely linked with the tau protein, is elevated in the cerebrospinal fluid and urine of AD patients. This study examined the association between urinary AD7c-NTP and late-life depression with cognitive impairment. One hundred and thirty-eight subjects were recruited into late-life depression with cognitive impairment (LLD-CI, n=52), late-life depression without cognitive impairment (LLD-NCI, n=29), AD (n=27), and healthy control (HC, n=30) groups. The level of urinary AD7c-NTP was measured using the enzyme-linked immunosorbent assay method. The Montreal Cognitive Assessment scale (MoCA), Hamilton Rating Scale for Depression (HRSD) and Hamilton Anxiety Rating Scale (HAMA) were used to assess cognitive functions and depressive and anxiety symptoms in the AD and LLD groups. Urinary levels of AD7c-NTP in the LLD-CI group (1.0 +/- 0.7ng/ml) were significantly higher than both the LLD-NCI (0.5 +/- 0.3ng/ml) and HC groups (0.5 +/- 0.3ng/ml), but lower than in the AD group (1.6 +/- 1.7 ng/ml). No significant associations were found in the level of urinary AD7c-NTP in relation to age, gender, education and MoCA in the LLD-CI group. The level of urinary AD7c-NTP appears to be associated with cognitive impairment in late-life depression and may be a potential biomarker for early identification of cognitive impairment in LLD.