The immortality characteristics of the cancer cells is contributed by the maintenance of telomere lengths. Telomerase, a protein involved in elongation of the telomeres occurs in approximately 80% of cancers (1). The remaining cancers involve a mechanism which is independent of telomerase known as Alternative Lengthening of Telomeres (ALT) and Ever Shortening Telomeres (EST). A preliminary screening for ALT (C-circles) and Telomerase (qTRAP) in 384 cancer cell lines was performed. We discovered a few cancer cell lines with dual-telomere maintenance mechanism (Dual-TMM) indicated by the low levels of C-circles and telomerase activity. Further identification of the ALT characteristics in the cell lines were showed promising results that this is the case.