This paper is devoted to online marketing tools and primarily focuses on the use of social networks and measuring their effectiveness. The theoretical part briefly presents the topic of online marketing and selected tools. The next section deals with the case study that analyses the use of social networks on a particular project, including measuring the efficiency of social networks by comparing the planned and actual state according to the selected metrics. In conclusion, there is a discussion on the results obtained and the possible directions, which would increase the efficiency of social networks, i.e. online marketing, are outlined. The results of assessing the current state of online marketing for the surveyed project in 2017, by comparing the planned and actual metric values, largely fail to meet the targets. With measuring social networking tools, the planned numbers of website visits and social networking orders didn’t reach their planned values. Regarding the number of fans on individual social networks, the planned status was only achieved with the Pinterest and Instagram social networks.