microRNAs (miRNAs), regulatory non-coding RNAs, can change translation, and decrease protein expression. miR-16 and miR-34a families are among the most abundant tumor suppressors and highly conserved microRNAs recognized. They have vital regulatory roles in health and disease. Their regulatory functions include biological processes such as improvement, differentiation, cell death, survival, and cell metabolism. The use of miR-16 and miR-34a families as biomarkers for cancer treatment is likely to improve patients with cancer. In this review, we update on recent advances in understanding the mechanism of miR-16 and miR-34 families function in cancer. Knowing about these mechanisms is effective for improving drugs and treatment methods. We also evaluated the reviewed studies and by introducing their weaknesses, we made suggestions for improving future research.