Lung cancer is one of the leading causes of death in the western world and is accompanied by the early development of metastasis. The ability of tumor cells to migrate is of great importance for the metastatic process. In addition to cytoskeletal mechanisms several members of Ca²⁺-activated K⁺ channels, and in particular K_Ca3.1, have been shown to be involved in cell migration. Here, we compared two strains of the lung carcinoma cell line A549 with low and high metastatic potential. The class comparison analysis of microarray expression data revealed significantly increased expression of the Ca²⁺-activated potassium channel K_Ca3.1 in the highly metastatic A549 cell line. This result could be validated on the mRNA level using PCR or quantitative real-time PCR. In migration experiments, trans-well assays showed that the highly metastatic A549 cell line exhibited an increased migratory activity towards a higher serum concentration than the parental cell line with low metastatic potential. Migration of the A549 cells could be stimulated by epidermal growth factor (EGF) and was more efficient when using a collagen-based matrix, composed of collagen type I, III and IV as well as laminin and fibronectin. Moreover, we could observe an increase of migratory activity in the highly metastatic A549 cell line when using the K_Ca3.1 channel activator 1-ethyl-2-benzimidazolinone (1-EBIO). In conclusion, these results provide evidence that the the Ca²⁺-activated potassium channel K_Ca3.1 might be involved in the metastatic process.