Objectives: To determine whether environmental rearrangements of the long-term care nursing home can affect disruptive behavioral and psychological symptoms of dementia (BPSD) in residents with dementia. Design: Prospective 6-month study. Setting: The study was conducted before (phase 1) and after (phase 2) environmental rearrangements [skylike ceiling tiles in part of the shared premises, progressive decrease of the illuminance at night together with soothing streaming music, reinforcement of the illuminance during the day, walls painted in light beige, oversized clocks in corridors, and night team clothes color (dark blue) different from that of the day team (sky blue)]. Participants: All of the patients (n = 19) of the protected unit were included in the study. They were aged 65 years or older and had an estimated life expectancy above 3 months. Measures: Number and duration of disruptive BPSD were systematically collected and analyzed over 24 hours or during late hours (6:00-12:00 PM) during each 3-month period. Results: There was no significant change in the patients' dependency, risk of fall, cognitive or depression indexes, or treatment between phase 1 and 2. Agitation/aggression and screaming were observed mainly outside the late hours as opposed to wandering episodes that were noticed essentially within the late hours. The number of patients showing wandering was significantly lower over 24 hours during phase 2. The number of agitation/physical aggression, wandering, and screaming and the mean duration of wandering episodes were significantly (P = .039, .002, .025, and .026 respectively) decreased over 24 hours following environmental rearrangements. Similarly, a significant reduction in the number and mean duration of wandering was noticed during the late hours (P = .031 and .007, respectively). Conclusions: Our study demonstrates that BPSD prevalence can be reduced following plain environmental rearrangements aimed at improving spatial and temporal orientation.