Objective To investigate the relationship of serum gastrin level with severity of coronary lesions in the elderly patients with coronary heart disease (CHD). Methods A total of 104 elderly CHD patients who received coronary artery angiography (CAG) in our hospital from October 2015 to December 2016 were recruited in this study. According to their coronary artery stenosis, they were divided into CHD group (n=82) and control group (n=22). By the number of involved branches, the former group were further assigned into 3 subgroups:single vessel subgroup (n=42), double vessel subgroup (n=27) and triple vessel subgroup (n=13). The severity of coronary arterial stenosis was evaluated by Gensini scoring system. Enzyme-linked immunosorbent assay was used to measure the levels of fasting serum gastrin (FG) and postprandial 1 hour serum gastrin (PG1h). The measurement data were expressed as mean±standard deviation ([AKx-D]±s), and Student’s t test was employed for the comparison between groups. Enumeration data were expressed as percentage, and inter-group comparison was carried out with Chi-square test. Results There were no significant differences in age, sex, smoking, family history of CHD, gastrointestinal disease, serum level of creatinine (SCr), and usage of proton pump inhibitors (PPIs) between the CHD group and control group (P>0.05). The CHD group had significantly higher body mass index (BMI), triglycerides (TG), low density lipoprotein-cholesterol (LDL-C), FG, and FG1h, and notably larger proportions of hypertension and diabetes when compared with the control group (P<0.05). The patients with triple vessel disease had remarkably higher PG1h, ratio of PG1h/FG and Gensini score than those with single and double vessel disease (P<0.05). Spearman correlation analysis showed that serum gastrin level had no correlation with sex, BMI, smoking, family history of CHD, TG and LDL-C, but was correlated with age, gastrointestinal disease, usage of PPIs, hypertension, SCr, number of lesioned branches and Gensini score (P<0.05). After partial correlation analysis and correction of confounding factors, serum gastrin level was positively correlated with the number of lesioned branches (r=0.58) and Gensini score (r=0.63). Conclusion Serum gastrin is positively correlated with the lesion severity of coronary artery disease in elderly CHD patients. It suggests that higher serum gastrin might negatively contribute to the occurrence and development of coronary atherosclerosis in the elderly.