The aim of this study is to determine the relationship between work-related strain level and medical error tendency of the nurses. The present study was carried out in relational screening model. The data was obtained from 260 nurses. The study data were collected from four state hospitals in a province located in the Western Black Sea region in Turkey between January and March 2017. Approval from the Ethical Committee and institution and verbal consent from the nurses were obtained prior to conducting the study. A descriptive characteristics form, the Work-Related Strain Inventory (WRSI) and the Medical Error Trend Scale in Nursing (MTSN) were used to collect data. The evaluation of the data was done by descriptive statistics and correlation analysis. Nurses' work-related strain was found moderate, and their tendency to make medical error was low. A negative, significant, and very weak relationship was found between work-related strain in nurses and medical error tendency related to communication, prevention of falling, patient monitoring and equipment safety, prevention of infections, and medicine and transfusion practices. As a result of the study, it is seen that work-related strain in nurses affected the medical error tendency significantly and negatively.