Recent studies suggest that impulsivity fluctuates over time. It is unclear if state-impulsivity serves as a risk factor of suicidal ideation (SI) at a state level. A sample of 74 psychiatric inpatients with depression (M = 37.6 years, 72% female) and SI completed baseline measurements and an ecological momentary assessment over a 6-day period. Despite considerable within-person variance, state impulsivity was not significantly associated with clinical characteristics (depression, baseline SI, past suicide attempts). Daily variability of passive SI showed a significant prospective association with state impulsivity. Limiting factors are the small sample size and the short observation period.