This master degree thesis is discussing the online reference services, since they enable anybody to ease his life by using them. They are able to provide information to the user who has no need to leave the house, but to be connected to the Internet. Furthermore, the user is always able to set any question no matter the time. Among such services, there are so called the commercial ones providing answers to any questions provided by anybody as well as the library services that involve experts to give proper answers. Both services involve various possible ways of communication of which the most common is inserting the question into the specific field to be consequently given the answer on it within a certain period of time. The fundamental task of this master degree thesis is the presentation of the quality of answers provided by online reference services - the ones which answers are provided by the users as well as those that employ librarians. The comparison, however, unveiled the services which answers were found to be of the best quality and also their significant deficiencies. Much attention was also paid to the familiarity and use of reference services and to the findings about which reference services were found more trustful and why. The gained results enable a better future work of reference services, since the research discovered groups of insufficient answers provided. Furthermore, the reasons why users showed eventual distrust at using particular reference services were also presented.