It is important to evaluate the impact of clinical information systems on the quality and timeliness of documentation in the patient's record to ensure the systems are improving clinical care processes and providing value to the organization. An observational study was conducted to measure the accuracy and timeliness of vital signs data during three different stages of clinical documentation system implementation at a large academic medical center: (1) a paper medical record system, (2) a clinical documentation system with "computers on wheels" workstation outside the patient's room, and (3) a clinical documentation system with a Tablet PC affixed to the vital signs monitor. Patient observations (n = 270) were completed as patient care technicians made routine vital sign rounds. Equipping patient care technicians with a Tablet PC affixed to the vital signs monitor significantly improved (P < .05) the accuracy and timeliness of vital signs. In addition, a number of unintended consequences were discovered that proved helpful to the nurse managers and nursing informatics leadership team in providing support of the new system. Findings from this study emphasize the importance of ensuring that staff has the appropriate devices needed to effectively document patient care at the bedside.