Background & Aims: Risk factors for small intestinal neuroendocrine tumors (siNETs) are not well understood. The aim of this systematic review was to assess if smoking, alcohol and family history of cancer are risk factors for siNETs. Methods: MEDLINE and abstracts from the ENETS and NANETS were searched for studies published until May 2015. Eligible studies were selected according to the PRISMA statement. Results: Seven studies evaluating six individual populations were included (study accrual period 1961-2012) in the meta-analysis, involving 1872 (range 17-1107) cases and 508,445 (range 52-498376) controls. All studies were case-control studies. The pooled adjusted OR was 1.34 (95% CI 1.12-1.60; p<0.01; I2=0.0%) for family history of any cancer, 1.43 (95% CI 1.15-1.79; p<0.01; I2=0.0%) for family history of colorectal cancer, 1.04 (95% CI 0.63-1.72; p=0.87; I2=65.0%) for ever alcohol use, and 1.40 (95% CI 1.06-1.86; p<0.05; I2=49.3%) for ever smoking. Conclusions: Family history of any cancer, family history of colorectal cancer and history of ever smoking are associated with an increased risk of siNET.