Transition from Analogue Terrestrial Television Broadcasting to Digital Terrestrial Television Broadcasting (DTTB) in the 470-862 MHz band made available amount of spectrum so-called digital dividend for other services i.e. 790-862 MHz band (800 MHz) to mobile service. Recently the 694-790 MHz band (700 MHz) was also allocated to mobile service in ITU Region 1. Spectrum allocated to a broadcasting service but not used locally is called as TV white spaces (TVWS). It is possible to introduce TVWS services in 470-790 MHz band under the condition that other services in this band already operating, or planned in the country and in neighboring countries, are adequately protected and this use does not violate the current ITU Radio Regulations. TVWS under some conditions locally could be used for mobile communications systems e.g. unlicensed Wireless Fidelity (Wi-Fi) using cognitive radio. As TVWS are located in the UHF band, the use of TVWS can provide significantly better coverage and wall penetration inside buildings than 2.4 GHz and 5 GHz range Wi-Fi frequencies. The exact amount of available spectrum for TVWS at any location will be dependent upon each country national situation e.g. DTTB planning configuration, other services use in the band. In case of deploying Wi-Fi in the TVWS the interference impact of Wi-Fi on DTTB has to be taken into account. The aim of this paper is to analyze the interference impact of Wi-Fi on DTTB. In this paper the interference occurring probability in DTTB receiver was evaluated by using Spectrum Engineering Advanced Monte-Carlo Analysis Tool (SEAMCAT).