This study aims to evaluate the efficacy of a psychotherapeutic intervention model in nursing on nursing diagnosis "Anxiety" (according to International Classification for Nursing Practice (ICNP)/North American Nursing Diagnoses Association (NANDA) standardized nursing language). A randomised controlled trial will be carried out to do so. In a single-blinded nurse-led 6 months controlled trial, conducted at a hospital outpatient setting in Portugal, approximately 60 patients with anxiety will be randomised to the intervention (n=30) or control groups (n=30). The objective is to compare the outcomes associated with "treatment-as-usual" and the benefits of implementing the psychotherapeutic intervention model in nursing previously developed (5 sessions), which will be evaluated using Nursing Outcomes Classification (NOC) outcomes "Anxiety Level" and "Anxiety Self-Control" (Portuguese version).