An understanding of the clinical features of gastric cancer (GC) in hereditary diffuse gastric cancer (HDGC) families may be helpful in deciding who should receive prophylactic total gastrectomy and when. This study evaluates the sex ratio and age of onset features of these patients. Forty-seven HDGC families were screened from the English (40 families), Chinese (7 families) literature. One family was ascertained in our hospital. A total of 48 HDGC families with 192 GC cases were analyzed. The patients were grouped as Asian and non-Asian cases according the first author corresponding address. The male to female ratio of GC patients in our study was less than general GC population (0.769 vs. 1.826, P < 0.0001). The mean age of male cases was higher than that for females (48.9 vs. 43.1 years; P = 0.012). The mean age for parents of cases was higher than that for the offspring of cases (52.5 vs. 37.4 years; P = 0.0001). There was a significant age correlation between sib-sib GC pairs (P < 0.0001). The male to female ratio of Asian GC patients was higher than that of non-Asian GC cases (1.450 vs. 0.614, P = 0.01). The age for Asian GC patients was higher than that of non-Asian GC patients (52.1 vs. 43.5 years, P = 0.001). The results showed that female GC patients were more frequent and younger than male patients in HDGC families. The parents of cases were older than offspring cases. There was a significant age correlation between sib-sib cases. There was regional disparity in the sex ratio and age features.