Scam products, empty promises and expensive mistakes. Ultrasonic Rat repellers have been on sale for over 40 years - but when experts have scrutinised them, it turns out: almost all of them are ineffective. Only one model has been proven to work for real - the Swedish innovation Repello.
👉 Read more about Repello and order here
The scams revealed
Rat repellers are sold everywhere - in DIY stores, online shops and auctions. Manufacturers promise to 'cover 300 square metres', 'penetrate walls' or 'send pulses into the power grid'.
But according to Professor Ă–rjan Johansson vid LuleĂĄ University of Technology It is Physically impossible.
- Ultrasound is quickly attenuated in air and stopped by walls. "The devices sound technical, but in practice many do nothing at all," says Johansson.
Also National Association of Homeowners och Swedish Consumer Agency has been warning about misleading marketing for decades. As early as the 1990s, parts of the market were labelled "bluff product", as the devices had no measurable effect.
Swedish research cracked the code
After several years of research in LuleĂĄ, Johansson's team managed to identify the sound that rats themselves use to warn the pack - a rapid Tandgnissel which means Danger to life.
- "When we recreated that sound in the lab, we saw how the rats fled immediately, without returning," says Johansson.
This technology became the basis for Repello - the first rat scare in the world to imitate the rats' own warning language. The rhythm and frequency of the signals are constantly changing, allowing the rodents to can't get used to.
Research proved the effectiveness
In a field trial together with Swedish University of Agricultural Sciences (SLU) 44 rats were documented in a property in Gothenburg. When Repello was activated, they all disappeared within seconds - and none returned for the next two weeks, despite the presence of food and shelter.
The result: 100% reduction in rat activity.
- "This is the first time we've been able to scientifically demonstrate that a rat repeller works in practice," says Johansson.
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Named Best in Test 2025
Repello is the only product that has been able to convince both scientists and independent test panels of its true effectiveness. It has been recognised as Best in Test 2025 of both Home news och The best-in-test guide, both of which emphasise their unique scientific basis.
🏆 Villa News (24 Sep 2025) - "The only rat repellent with verified scientific efficacy. All other models failed."
🏆 Best-in-Test Guide (10 Oct 2025) - "Repello is the only mouse repellent that gets mice and rats to leave the area completely without poisons."
Non-toxic and child safe
Repello is completely chemical-free and harmless to children, dogs and cats. It plugs directly into an electrical socket and covers approximately 40 m². For larger areas, multiple units are recommended. Operation is virtually silent, and many people use it even in bedrooms or basements.
- "It's a simple and sustainable solution that replaces poisons and traps," says Repello's founder Mikael Eriksson.
Why Repello won all the tests
âś… Scientifically documented effect (LTU + SLU)
âś… Non-toxic and safe for pets and children
âś… No habituation - variable bioacoustic signals
âś… Quiet, energy-saving and easy to use
âś… Effective against both rats and mice
After decades of ineffective devices, there is finally a solution that really works.
Repello is the only rat repellent with scientifically proven efficacy and a rating of Best in test 2025 in both Villanytt and the Best-in-Test Guide.
