Purpose: To investigate the correlations of pulmonary high-resolution computed tomography (HRCT) findings and their distribution with the peripheral blood immunological parameters of swine-origin influenza A (H1N1) infection. Materials and methods: 173 patients with H1N1 influenza infection underwent HRCT. CD4+ and CD8+ lymphocyte counts and C-reactive protein (CRP) levels in the peripheral blood were measured on the day of admission. According to the predominant HRCT findings, we created three groups: Group A = normal attenuation, Group B = ground-glass opacity (GGO), Group C = consolidation with or without GGO. We classified the extent of lung lesions into five groups as follows: Group 1 = CT score of 0; Group 2 = CT score of 0.01–0.25; Group 3 = CT score of 0.26–0.50; Group 4 = CT score of 0.51–0.75; Group 5 = CT score of 0.75–1.00. Results: The CD4+ and CD8+ lymphocyte counts decreased with the degree of the attenuation and the extent of the lesions on HRCT (P < 0.001), whereas the CRP levels increased with the degree of the attenuation and the extent of the lesions (P < 0.001). Conclusions: The HRCT findings correlated with the CD4+ and CD8+ lymphocyte counts and the CRP level in the peripheral blood of patients in the initial stage of influenza infections.