To investigate frameshift mutations of microsatellite sequence in and genes in acute lymphoblastic leukemia (ALL) with microsatellite instability (MSI). Methods Fluorescent frag-ment PCR was used for defining the microsatellite status of ALL cells both in cell lines and bone marrow samples. Sanger sequencing and fluorescent fragment PCR were used for the detection of frameshift mutations of microsatellite sequences in and genes in ALL cells with MSI both in cell lines and bone marrow samples. Results The incidence of MSI in the ALL cell line was 80.0% (4/5). The incidence of MSI in the child ALL cells was 25.0% (3/12). The incidence of MSI in the adult ALL was 20.0% (2/10).Frameshift mutations of c.22delC in gene and c.2560delA in gene were detected in Molt4 cell line. Frameshift mutation of c.22delC in gene was detected in CCRF-CEM cell line. None of the above frameshift mutations was detected in the ALL bone marrow samples. Conclusions MSI induced and gene frameshift mutations occur in the ALL cell lines.