Background L1 cell adhesion molecule (L1CAM) overexpression has been reported to be strongly associated with poor prognosis in early stage endometrial cancer (EC). We aimed at the validation of L1CAM as a marker of poor prognosis in an independent study population. Methods Patients with endometrioid EC FIGO stage I, were treated at Oslo University Hospital between 2005 and 2012. L1CAM expression was detected by immunohistochemistry with >10 % L1CAM staining defined as positive. Risks of relapse and death were estimated as hazard ratios (HRs) with 95 % confidence intervals (95 % CI). Results Of 450 patients, 388 (86 %) were evaluable for L1CAM expression and 35 (9 %) were L1CAM positive. After follow-up for a median time of 4.8 years (0.1–8.8), 33 (8 %) patients had recurred. 6/35 (17 %) L1CAM positive patients relapsed compared to 27/353 (8 %) L1CAM-negative patients. There were 7 (20 %) deaths in the L1CAM positive group, and 34 (10 %) in the negative group. In multivariate analysis, controlled for age and FIGO stage, L1CAM positivity was not significantly associated with the risk of relapse (HR 2.08, 95 % CI: 0.85–5.10, p = 0.11) or death of all-cause (HR 1.81, 95 % CI: 0.79–4.11, p = 0.16). In patients who were not treated with chemotherapy, L1CAM was significantly associated with risk of relapse (HR 2.9; 95 % CI: 1.08–7.56; p = 0.04). Conclusion Our report confirms that L1CAM is associated with a more aggressive tumortype and more distant relapses. The overall recurrence rate in this population was low as were the absolute differences between L1CAM positive and negative patients. In this independent study sample, L1CAM failed to be a clinically relevant marker of poor prognosis in stage I endometrioid endometrial carcinoma.