Low serum carnitine levels have been reported in patients with cancer receiving chemotherapy and are considered one of the factors causing fatigue associated with chemotherapy. We evaluated the effectiveness of L-carnitine in the treatment of fatigue associated with chemotherapy in patients with gastric cancer(GC).We performed a randomized controlled trial between December 2013 and December 2018. Untreated patients with advanced GC were included in the study; 1 patient developed an allergy after receiving the first chemotherapy and was excluded from the study. The primary endpoint was brief fatigue inventory(BFI). Patients were categorized into 2 groups: those who received L-carnitine oral supplements(group C)and those who did not receive L-carnitine oral supplements(group N).The serum carnitine levels were improved significantly in group C compared with group N. BFIwas more aggravated in group N than group C; however, the difference was not significant.We could not demonstrate the effectiveness of L-carnitine in the treatment of fatigue associated with chemotherapy in patients with GC.