OBJECTIVE: The purpose of this study was to determine the effects of an interactive multimedia internet-based system (IMIS) for the cognitive stimulation of Alzheimer's disease (AD). METHODS: This is a 24-week, single-blind, randomized pilot study conducted on 46 mildly impaired probable AD patients receiving stable treatment with cholinesterase inhibitors (ChEIs). The patients were divided in three groups: 1) Received 3 weekly, 20-minute sessions of IMIS plus 8 hours per day of an integrated psychostimulation program (IPP), 2) Received only IPP sessions; and 3) Received only ChEIs therapy. The primary outcome measure was the Alzheimer's Disease Assessment Scale-Cog (ADAS- Cog). Secondary outcome measures were: Mini-Mental State Examination (MMSE), Syndrom Kurztest (SKT), Boston Naming Test (BNT), Verbal Fluency and the Rivermead Behavioral Memory Test (RMBT) story recall subtest. RESULTS: After 12 weeks, the patients treated with both IMIS and IPP had improved outcome scores on the ADAS-Cog and MMSE; this was maintained through 24 weeks of follow- up. The patients with the IPP alone had better outcome than the ChEIs alone group, but the effects were attenuated after 24 weeks. All subjects improved their scores in all of the IMIS individual tasks, attaining higher levels of difficulty in all cases. CONCLUSION: Although both the IPP and IMIS improved cognition in AD patients, the IMIS program provided an improvement above and beyond that seen with IPP alone, and which lasted for 24 weeks.