The present study was performed to clarify the effect of hypertonic saline infusion into the lung parenchyma on radiofrequency ablation (RFA) of the lungs. A total of 20 ablation zones were created in 3 pigs. The ablation zones were divided into 3 groups. Group 1 (n = 6) consisted of ablation zones created by applying smaller radiofrequency (RF) power without saline infusion; group 2 (n = 5) zones were created by applying greater RF power without saline infusion; and group 3 (n = 9) zones were created by applying greater RF power with saline infusion. The techniques of saline infusion included administration of hypertonic saline 1 ml before RFA, followed by continuous administration at a rate of 1 ml/min during the first 2 min after the initiation of RFA. The ablation parameters and coagulation necrosis volumes were compared among the groups. Group 3 had a tendency toward smaller mean impedance than group 1 (p = 0.059) and group 2 (p = 0.053). Group 3 showed significantly longer RF application time than group 2 (p = 0.004) and significantly greater maximum RF power than group 1 (p = 0.001) and group 2 (p = 0.004). Group 3 showed significantly larger coagulation necrosis volume (mean, 1,421 mm(3)) than group 2 (mean, 858 mm(3), p = 0.039) and had a tendency toward larger necrosis volume than group 1 (mean, 878 mm(3), p = 0.077). Although this small study had limited statistical power, hypertonic saline infusion during RFA appeared to enlarge coagulation necrosis of the lung parenchyma.