AIM:To evaluate the epidemiologic features of young age gastric cancer(GC). METHODS:Retrospectively,a total of 3242 patients with GC between 18 and 45 years of age and 3000 sex-and age-matched controls were reviewed.All subjects were stratified into 3 groups based on age (A,18-30 years;B,31-40 years;C,41-45 years). Epidemiologic characteristics and risk factors were investigated with reference to their age and gender. RESULTS:Compared to controls,more frequent intake of high risk diet(P=0.00075),history of heavy smoking(P=0.00087),intake of heavy alcohol(P= 0.00091),lower social economic status(P=0.00083), body mass index>30(P=0.00097),urban residence(P=0.00065),and more frequent exposure to harmful occupational environments(P=0.00072)were observed in all age groups and both genders in young age GC.These relationships were weaker in females compared to males of the same age,and were stronger as the age of patients increased.However,in group C of young age GC patients,environmental factors played important roles in females and males with a similar body weight.In females,older age at first delivery(> 35 years),lack of lactation history,nulliparity,and poor nutritional status during pregnancy were significantly associated with an increased risk of GC(P=0.00034). In this study,252 patients(7.8%)had a family history of GC with high odds ratio(OR)(3.22-4.21).In particular, family history was more closely associated with GC in males(OR,4.21 in male vs 3.46 in female)and more advanced cases(P=0.00051). CONCLUSION:Hormonal associated factors were more commonly associated with females whereas environmental factors were more commonly associated with males in young age GC patients.