This research investigates the influence of priority road markings on cyclists’ behaviour at bicycle street crossings. Almost all bicycle street crossings are controlled by priority markings or by the priority rule: traffic coming from the right has priority. At these crossings there is a lot of interaction between cyclists, so it is important that the bicycle traffic can pass the crossings without severe conflicts. For the research two crossings were observed. One crossing with priority markings and one without priority markings, both with traffic from four directions. At both crossings a camera recorded the cyclists passing the crossing for one hour at three different moments in the day. The conflicts on the footage are investigated in the analysis. Firstly, It was investigated if priority was given when it should have been given. Also the severity of the conflicts and the behaviour of the cyclists who had to give priority were classified. Finally the influence of the kind of crossing (crossing or merging), the influence of groups and the influence of scooters were addressed. The results show no relation between the presence of a scooter in a conflict and the percentage of cyclists not giving priority while they should have given priority. Also merging and crossing conflicts show no large difference in priority behaviour. But when groups are part of a conflict, priority is less often given while it should have been given. After these three influences, conflicts in general are compared for a crossing with priority markings and a crossing without priority markings. The observed crossing without priority markings shows a larger percentage of severe conflicts. Also the cyclists who had to give priority show more often reckless behaviour in conflicts. From these results it is concluded that priority markings control the priority on a crossing better than the priority rule: traffic coming from the right has priority.