The purpose of this retrospective study was to evaluate the value of preoperative percutaneous CT-guided fine needle aspiration biopsy (CTNB) for peripheral lung cancers less than 2 cm in size, especially in cases showing of ground-glass opacities (GGO). From 1999 to 2002, 151 small lung cancers were resected in Tokyo Medical University Hospital. Among them, 96 patients (63.6%) in whom the lesions were located in the outer half of the lung field underwent CTNB in order to obtain a preoperative diagnosis. The factors influencing the diagnostic yield were analyzed. The overall diagnostic yield of CTNB was 64.6%: 48.5% for lesions smaller than 10 mm, 62.5% for those 11-15 mm, and 83.9% for those 16-20 mm, respectively. The diagnostic yield in GGO-dominant lesions (GGO ratio < 50%) and solid-dominant lesions (GGO ratio < 50%) were 51.2% and 75.6% (p = 0.018). In the GGO-dominant group, the diagnostic yields were 35.2% for lesions smaller than 10 mm, 50.0% for those 11-15 mm, and 80.0% for those 16-20 mm. In the solid-dominant group, diagnostic yield was 62.5% for cases smaller than 10 mm, 75% for 11-15 mm and 85.7% for 16-20 mm, respectively. Satisfactory diagnostic yield (>80%) was obtained by CTNB in cases larger than 15 mm. CTNB is a useful diagnostic modality for peripheral small lung cancers; however, for GGO-dominant lesions, the preoperative diagnostic yield is not significantly better than for solid-dominant lesions.