Slowly growing lung cancers are quite rare and the leading cause of length time bias and over-diagnosis bias in lung cancer screening. We report 6 cases of slowly growing lung cancer in a tertiary hospital between January 1999 and December 2008. The clinical characteristics of these 6 cases with slowly growing lung cancer were examined. The median age at diagnosis was 68 years (range, 49~72), and 5 patients (83%) were female. The most common histology type was adenocarcinoma (83%). After excluding two patients who showed no change in the tumor size, the median tumor doubling time was 189 months (range, 86~387). The proportion of patients with slowly growing lung cancer appears to be particularly large in women, especially among patients with adenocarcinoma. Our experience shows that slowly growly lung cancers are more heterogeneous and diverse.