This study aims to investigate the effectiveness of the C-reactive protein/albumin ratio (CAR) and parameters derived from complete blood counts as indicators of inflammatory activity in patients with rosacea and to evaluate their association with disease severity. This retrospective cross-sectional study included 90 rosacea patients classified into three groups based on the Investigator Global Assessment (IGA) score: 30 with mild, 30 with moderate, and 30 with severe disease, along with 30 healthy controls. There were no significant differences between the patient and control groups in terms of gender (%31.1 vs. %30 male) and age (41.92 ± 10.70 years vs. 41.07 ± 11.92 years). In rosacea patients, neutrophil (P = 0.0004), lymphocyte (P = 0.031), platelet (P = 0.041), monocyte (P = 0.003), CRP (P <
0.0001), and CAR (P <
0.0001) levels were significantly higher. The AUC value for CAR was 0.83, with a cut-off value of 0.91
sensitivity was 66.67%, and specificity was 96.67%. Significant differences were observed among the three patient groups classified by rosacea severity for neutrophil (P <
0.0001), lymphocyte (P = 0.011), monocyte (P = 0.0001), CRP (P <
0.0001), albumin (P <
0.0001), CAR (P <
0.0001), neutrophil/lymphocyte ratio (NLR) (P = 0.004), and lymphocyte/monocyte ratio (LMR) (P = 0.021). Patients with rhinophyma had higher neutrophil (P = 0.005) and NLR (P = 0.019) levels. Those with ocular involvement had higher CRP (P = 0.003) and CAR (P = 0.002) levels, while albumin (P = 0.024) levels were lower. This study is the first to examine the relationship between CAR, rosacea severity, and different clinical types. Based on our findings, we believe that CAR and other hematological parameters can be used to assess the severity of rosacea and monitor various clinical types.