The present report describes three cases of a bronchiolitis obliterans organizing pneumonia (BOOP)-like reactive pneumonitis following radiofrequency (RF) ablation for lung cancer. The incidence of BOOP-like reactive pneumonitis after RF ablation at the authors' institution was estimated to be approximately 0.4% (three of 840 sessions). The patients presented with nonspecific symptoms. Computed tomography images showed consolidation or ground-glass opacity in a peripheral-dominant distribution and/or patchy air-space opacities. The disease was nonresponsive to antibiotic therapy but responded favorably to pulse therapy of steroids. BOOP-like reactive pneumonitis should be recognized as a complication following lung RF ablation.