As advanced gastric cancer often leads to obstruction or cancer-related cachexia, gastric cancer seems to have a closer association with sarcopenia than other types of cancer. Our study aim was to investigate the relationship between the psoas muscle area (PSMA) and morbidity and mortality in patients undergoing gastric cancer surgery. The data of patients who underwent laparoscopic gastric resection between November 2014 and April 2020 were analyzed retrospectively. The intervertebral disc space was verified at L3-4 in the sagittal plane. The PSMA on the right and left sides were measured separately and then added to obtain the total PSMA. This value was then divided by the patient's height (m2) to calculate the psoas muscle area index (PSMAI) (mm2/m2). The mean PSMAI of men (741.1 mm2/m2) was significantly higher than that of women (502.1 mm2/m2) (p<0.001). While there was a positive correlation between the PSMAI and BMI (r:0.352, p:0.019 in women; r:0.447, p<0.001 in men), the correlation between PSMAI and age was negative (r: -0.369, p:0.014 in women; r:-0.349, p<0.001 in men). PSMAI was statistically lower in patients with attendant morbidity (p:0.035). There was no significant relationship between PSMAI and the first 30-day mortality rate (p:0.096); however, the association between PSMAI and both the 90-day mortality rate (p:0.023) and the total mortality rate (p:0.046) were significant. In our opinion, assessing gastric cancer patients for sarcopenia and supporting them with the necessary nutrition and exercise program prior to surgery can help predict and lower postoperative morbidity and mortality rates.