Obsessive compulsive disorder (OCD) usually comes with obsession, but it can occur without obsessions. However, this is rare. In the rare cases where OCD occurs without obsessions, it presents only with compulsions. Examples of OCD with only compulsions include counting compulsions, avoid walking on sidewalk cracks compulsions, making everything in proper order compulsions, etc. In these examples, the compulsions are obvious, but the obsessions are not. In some of these cases, after careful assessment, the compulsions may be indeed connected to the triggering obsession (i.e. in counting compulsion, the person turns out to be obsessed with the number 20, and therefore has to count everything 20 times).
