We reviewed the medical record of a series of patients with synchronous multiple lung cancers (SMLC), in an attempt to identify the optimal treatment strategy for multiple ground-glass opacities (GGOs). From 2004 to 2010, 1223 patients underwent complete resection of non-small cell lung cancer. Among these, there were 67 patients (5.5%) with SMLC with at least 1 of the nodules showing GGO appearance. SMLC was divided into the main cancer (MC) which was a main target based on its tumor size or radiological invasiveness and sub-nodules. According to consolidation/tumor ratio (CTR) on thin-section computed tomography, 67 cases were classified into GG-group (MC showing GGO-dominant lesion; CTR≤0.5) and GS-group (MC showing solid-dominant lesion; CTR>0.5). There were 24 patients in the GG-group (36%) and 43 patients in the GS-group (64%). Surgical resections included 11 sublobar resections (SLs), 32 lobectomies, 19 lobectomy+SLs, and 4 bilobectomies. There were 39 patients with a total of 118 unresected GGOs after the initial surgery. Among them, the frequency of growth was 8% on a per-nodule basis with the median tumor doubling time of 1373 days, and new GGOs emerged in 15 patients (23%). Multivariate analysis demonstrated that larger size of MC and the GS-group was associated with poor prognosis, whereas growth of the residual GGOs, the development of new GGOs, or whether or not all GGOs were treated did not affect survival. The 5-year OS proportions were 95.8% for the GG-group and 68.0% for the GS-group (p=0.009), and 92.4% for a MC of ≤25 mm and 53.6% for a MC of >25 mm (p=0.008). Survival of patients with multifocal GGOs is strongly affected by radiological findings of the MC. Strict surgical control for MC could be most important.