["Visual and auditory cueing improve functional performance in Parkinson's disease (PD) patients. However, audiovisual processing shares many cognitive resources used for attention-dependent tasks such as communication, spatial orientation, and balance. Conversely, tactile cues (TC) may be processed faster, with minimal attentional demand, and may be more efficient means for modulating motor-cognitive performance. In this study we aimed to investigate the efficacy and limitations of TC for modulating simple (heel tapping) and more complex (walking) motor tasks (1) over a range of cueing intervals, (2) with/without a secondary motor task (holding tray with cups of water).", "Ten PD patients (71 ± 9 years) and 10 healthy controls (69 ± 7 years) participated in the study. TCs was delivered through a smart phone attached to subjects' dominant arm and were controlled by a custom-developed Android application.", 'PD patients and healthy controls were able to use TC to modulate heel tapping (F(3.8,1866.1) = 1008.1, p < 0.001), and partially modulate walking (F(3.5,1448.7) = 187.5, p < 0.001) tasks. In the walking task, PD patients modulated performance over a narrower range of cueing intervals (R(2) = 0.56) than healthy controls (R(2) = 0.84; group difference F(3.5,1448.7) = 8.6, p < 0.001). TC diminished synchronization error associated with performance of secondary motor task during walking in PD patients and healthy controls (main effect of Task (F(1,494) = 0.4; p = 0.527), Task X Group interaction (F(1,494) = 0.5; p = 0.493)).'] Does smartphone-based tactile cueing improve motor performance in Parkinson 's disease?