The purpose of this paper is to answer the following question: how does the trust of websites offering tourist services influence the manner of purchase of accommodation services and holiday packages? Data were obtained from 505 respondents via an Internet-based questionnaire between May and October 2015. All of the respondents were Polish Internet users. Individuals who both sought information on tourist services and purchased the services offline indicated that the websites of hotels, travel agencies, and tour operators are the most credible. Another group who held a high opinion of hotels and tourist intermediaries’ websites was composed of people characterised by the ‘research online, purchase offline’ (ROPO) effect or the reverse-ROPO effect. People who searched for information on holiday packages and bought them via the Internet held a lower opinion of websites of hotels, travel agents, and tour operators. Research indicates that with respect to the assessment of the credibility of websites offering tourist services, there are significant differences between individuals seeking information on tourist services online and those who purchase such services online.