Intracoronary stenting reduces the restenosis rate after percutaneous transluminal coronary angioplasty (PTCA). However, restenosis still occurs in 20% to 30% of patients after stenting. Management of in-stent restenosis has become a significant challenge in interventional cardiology. The efficacy of re-PTCA with a larger balloon was investigated for restenosis following Palmaz-Schatz stenting. Clinical and angiographic results were compared in 46 consecutive patients with in-stent restenosis after one Palmaz-Schatz stenting. Twenty patients underwent redilation with a slightly larger balloon than used at the stenting (Large group) and 26 underwent redilation with the same size balloon as at the stenting (Control group). The clinical factors, lesion characteristics, lesion length, reference diameter and minimal luminal diameter at re-PTCA for the in-stent restenosis did not differ significantly between the 2 groups. Minimal luminal diameter of the Large group after re-PTCA was significantly larger than that of the Control group (3.1 +/- 0.2 vs 2.9 +/- 1.2 mm, p < 0.05). Follow-up angiography showed that the minimal luminal diameter of the Large group was significantly larger (2.1 +/- 0.6 vs 1.7 +/- 0.6 mm, p < 0.05) and the re-restenosis rate of Large group tended to be lower than that of the Control group (15% vs 38%, p = 0.07). Re-PTCA for in-stent restenosis with a slightly larger balloon than used at the stenting reduces the re-restenosis rate.