Writing is one of the areas of learning that requires the simultaneous use of multiple physical, cognitive and affective skills. This study aimed to determine writing anxiety, writer's block and written expression success levels of middle school fifth-grade students according to various variables and to examine the effect of writing anxiety and writer's block levels on written expression success. The study group, which was formed by the simple random sampling method conducted with the relational screening model, consisted of 482 fifth grade students attending schools in the city center of Aksaray. The "Writing Anxiety Scale" and "Writer's Block Scale" adapted and developed by Özbay and Zorbaz (2011) were used for data collection. The compositions written by the students were evaluated with the "Writing Skills Analytical Rubric” (Sezer, 2005). As a result of the statistical analysis, it was determined that the students had a medium level of writing skills and a low level of anxiety. Writer's block was sometimes or occasionally observed in a significant part of the students. It was found that the higher the writing success was, the less writing anxiety and writer's block they had. It was determined that writer's block had a negative and significant effect on writing success. A significant and positive relationship was found between writing anxiety and writer's block. As the writing anxiety increases, the writer's block level also increases significantly. Moreover, it was also examined within the scope of the study whether students' writing anxiety, writer's block and written expression success differed significantly in terms of various variables. The findings obtained were discussed in light of the literature.