Objectives: The main objective of the research was to establish and analyse the correlation between the findings of the ambulatory test of vital toluidine blue staining and the pathohistological findings of oral mucosal lesions at the Chair of Oral Medicine and Periodontology of the School of Medicine and at the outpatient clinic for oral medicine of the Division for Dental Medicine of the Department of Maxillo-facial Surgery of the University Hospital of Split. Materials and methods: The total of 30 patients with a pathological change in the oral mucosa participated in the research on a voluntary basis. Oral medicine specialists obtained a detailed medical history of the patients and performed a clinical examination. After the clinical examination, staining of a suspected lesion of the oral mucosa with toluidine blue and biopsy of the lesion for pathohistological analysis were performed. The data were entered into spreadsheets and descriptive statistics was conducted. Results: Out of the total number of 30 respondents, the diagnosis of OLP, as well as the diagnosis of leukoplakia, were confirmed in 10 respondents (33%). A total of five respondents (17%) had cheilitis actinica, while squamous cell carcinoma was confirmed in two respondents (7%). A total of five respondents (17%) tested positive for toluidine blue stain. All five pathological lesions that tested positive for toluidine blue stain were immediately clinically suspected of malignancy. Epithelial dysplasia was detected in two respondents (6.5%) by means of pathohistological analysis, while squamous cell carcinoma was detected in two respondents (6.5%). The toluidine blue stain test was positive in one respondent with OLP, while pathohistological analysis did not indicate the presence of epithelial dysplasia. Findings: Based on the obtained results, a positive correlation between the ambulatory test of vital toluidine blue staining and pathohistological finfing of the biopsied suspicious lesions can be confirmed. The toluidine blue stain test is used in the differential diagnosis of oral lesions and ulcerations of various etiologies according to malignant changes in the mouth. The advantages of this test are the ability to define areas that may be malignant or abnormal. Vital staining helps assess the extent of a potentially malignant lesion for excision, especially when it comes to diffuse, large lesions, or multilocular lesions. Unfortunately, this test is not 100% specific. Although none of the additional diagnostic tests can completely replace tissue biopsy and pathohistological analysis, the toluidine blue stain test has nevertheless proved to be a valuable additional diagnostic tool in the case of potentially premalignant and malignant oral lesions.