Improving adherence to hand hygiene (HH) of healthcare workers (HCWs) is a challenge for health institutions, and the use of technologies has been considered an important strategy within this process. Methods: To evaluate the impact of the use of alcohol-based hand rub gel (ABHR) dispensers with light sensors on the adherence to HH by HCWs. This is a prospective quasi-experimental study with comparative analysis between two 4-bed adult intensive care units at a private, tertiary-care hospital conducted over 22 weeks. An approach detection module with an LED lamp was attached to the ABHR dispenser. As a healthcare personnel approached it, the sensor was activated, and a red light turned on as a visual stimulus for HH. The color of the light changed to blue when HH was performed. All ABHR dispensers had electronic counters, but light sensors were installed only in the 4-bed dispensers of the intervention unit. Throughout the period, direct observation of adherence to HH was performed by 4 nurses who had previously been rated with an excellent coefficient of agreement (κ test = 0.951 and 0.902). At the end of the study, a perception survey was performed with the HCWs. Results: The median activation of ABHR dispensers per week was higher in the intervention unit with 1,004 (IQR, 706–1,455) versus 432 (IQR, 350–587) in the control group (P < .001). The same occurred when compared to the median activation per 1,000 patient days, with 53,069 (IQR, 47,575–67,275) versus 19,602 (IQR, 15,909–24,500) in the control group (P < .001). However, there was no evidence of difference in adherence to HH during direct observation between the 2 groups: 51.0% HH compliance (359 of 704) in the control group and 53.8% HH compliance (292 of 543) in the intervention group (P = .330). The same result emerged when we evaluated the “My Five Moments for HH” and by professional category. HCWs (N=66) answered the perception survey: 66.6% stated that lighting devices caught their attention regularly or most of the time and 59% agreed that the devices motivated HH. Conclusions: Using light sensors in ABHR dispensers can be an effective technology for improving HH. This finding was evident in the evaluation of the number of uses of the ABHR dispensers and in the HCW perceptions. Although direct observation did not show statistical evidence of difference between the groups, adherence was higher in the intervention group.