Objective: The present study aimed to examine the effect of the Problem-Solving Therapy (PST) based psychiatric nursing approach on the mental symptom levels of nursing students showing mental symptoms. Methods: The study was conducted in the semi-experimental design with a single group and pretest-posttest application. Study population consisted of 262 first-year students attending a nursing faculty in the 2016-2017 academic years. The data of the study was collected using the Introductory Information Form and Brief Symptom Inventory (BSI). The sample included seven students with a mean score of 2.00 or over on the Disease Severity Index (DSI). PST was implemented in seven-eight sessions of 40-45 minutes on average individually for each student. Data was assessed using descriptive analyses, test for the significance of the difference between independent groups and Paired Sample Wilcoxon Signed Rank Test. The level of statistical significance was accepted as p<0.05. Results: When the study population was evaluated in terms of DSI scores, it was seen that 22.1% of the students (3.4%, DSI≥2.00, n=9 and 18.7%, 1.99≥DSI>1.00, n=49) had psychopathologic tendencies. Following the PST, a decrease was found in the total scores of the sample on the BSI and whole subscales except for the Additional Findings subscale (p=0.89, p>0.05) (p<0.005). In addition, the difference between the mean scores on the DSI before and after the intervention was found statistically significant (p<0.005). Conclusion: It was determined that PST-based psychiatric nursing approach had a positive effect on nursing students with mental symptoms. It is recommended that PST be applied in larger sample groups in university students with severe mental symptoms and its effectiveness should be tested with randomized controlled studies.