<h4>Background</h4>This study examined negative symptom dimensions and their biological correlates in patients with schizophrenia under routine hospital conditions.<h4>Objective</h4>To assess whether demographic, clinical, and inflammatory markers, that is, C-reactive protein (CRP), complement component 4 (C4), and the neutrophil-to-lymphocyte ratio (NLR), contribute to variation across negative symptom domains measured using two complementary instruments.<h4>Methodology</h4>A cross-sectional study was conducted at the Clinics I-II of Psychiatry, Cluj-Napoca, Romania (May-September 2023). Here, C4A is linked to schizophrenia.