BACKGROUND:Diastasis of the rectus abdominis muscle (DRAM) is common during and after pregnancy. OBJECTIVES:To determine the association between: the presence of DRAM and low back pain, lumbo-pelvic pain, incontinence, pelvic organ prolapse, abdominal muscle performance or health-related quality of life; and between DRAM width and severity of these outcomes. DATA SOURCES:Six electronic databases (EMBASE, Medline, CINAHL, PUBMED, AMED and PEDro). STUDY SELECTION:Included studies of all designs with adults with DRAM that assessed low back pain, lumbo-pelvic pain incontinence, pelvic organ prolapse, abdominal performance or health-related quality of life. STUDY APPRAISAL & SYNTHESIS METHODS:Methodological quality was assessed using the Effective Public Health Practice Project tool. A narrative summary was completed for DRAM presence and presence of the various musculoskeletal dysfunctions, and DRAM width and the severity of these dysfunctions. RESULTS:Twelve studies involving 2242 participants were included. There was no significant association between the presence of DRAM and lumbo-pelvic pain or incontinence. There was a small association between the presence of DRAM and pelvic organ prolapse. DRAM width may be associated with health-related quality of life, abdominal muscle strength and severity of low back pain. LIMITATIONS:Quality of studies was weak. There was variability in the methods used to assess DRAM. CONCLUSION:There is weak evidence that DRAM presence may be associated with pelvic organ prolapse, and DRAM severity with impaired health-related quality of life, impaired abdominal muscle strength and low back pain severity. Systematic Review Registration Number: PROSPERO CRD42017058089.