Pneumonitis is a rare but severe and potentially fatal adverse effect in chemotherapy of lymphoma. This study is aimed to investigate the incidence of interstitial pneumonitis in non-Hodgkin's lymphoma (NHL) patients receiving immunochemotherapy with pegylated liposomal doxorubicin and rituximab. Lymphoma patients were retrospectively reviewed, and eligible patients were included in this study. According to the chemotherapy regimens, patients were classified in four groups: combination of vincristine, cyclophosphamide, doxorubicin, and prednisone (CHOP group) with rituximab (RCHOP group) and combination of vincristine, cyclophosphamide, pegylated liposomal doxorubicin and prednisone (CDOP group) with rituximab (RCDOP group). Incidence and severity of interstitial pneumonitis were compared among the four groups. Among 757 patients reviewed, 207 patients were included in final analysis. Thirteen patients developed chemotherapy-induced interstitial pneumonitis, and the mean cycle of chemotherapy before the onset of pneumonitis was 4. Incidence rates of pneumonitis were 0, 1.8, 17.4, and 21.1% in CHOP, RCHOP, CDOP, and RCDOP groups, respectively (p < 0.001). The mean grades of pneumonitis were 0, 2, 2.5, and 3 in four groups, respectively (p < 0.001). After adjustment of confounders, chemotherapy regimens (OR 3.491, 95% CI 1.527-7.981, p = 0.003) and neutropenia in previous cycles (OR 2.186, 95% CI 1.281-3.731, p = 0.004) were independently associated with the incidence of pneumonitis. Interstitial pneumonitis should be highlighted in NHL patients who received more than 4 cycles of RCDOP chemotherapy regimen, especially in those who had grade 4 neutropenia in the previous cycles of chemotherapy.