In the present study, sequencing approach has been adopted for exploring the genetic alteration of sequences for the ubiquitin gene (UBC) in patients of breast and lung cancer and comparing the results with a normal sequence that obtained from NCBI. The aim of this study was to detect for genetic alterations of UBC gene in the breast and lung cancer patients then compare with healthy control subjects, to investigate the association between the mutations at the intron region of the UBC gene and cancer disease, 40 blood samples were examined from patients with breast and lung cancer aged ranged from (17-65) years, were collected at Al-Amal Hospital of cancer in Baghdad province/Iraq, the period of collecting samples were from October/2018 to January/2019. While twenty-two blood samples from healthy control subjects were collected at ages ranged from(19-59). After DNA extraction, the PCR primer was designed to amplify the region in the UBC gene (part of exon 1 and the whole intron). Here we report the polymorphism of the intron sequence of the UBC gene in Iraqi population as the results of sequencing the PCR amplified products showed three different transition mutation G→A, C→T, T→C in patients with breast cancer were also appeared in healthy control subjects. While nine transition mutations appeared in lung cancer patients, at different locations of the sequence were detected by BLAST tool.