Experience with lymph node involvement (LNI) in ovarian serous tumors of low malignant potential (OSLMP) is limited, which has led to an uncertainty about the clinical significance of this phenomenon. In this study, we present the clinicopathologic features of 36 cases of OSLMP with LNI. A control group of 36 OSLMP with no LNI was established for comparison. Parameters recorded for both the study and the control group included Federation of International Gynecology and Obstetrics (FIGO) stage, microinvasion and micropapillary/cribriform pattern in the OSLMP, invasive and noninvasive peritoneal implants, the total number of lymph nodes, the number of lymph node sites sampled and their location (pelvic, periaortic, and abdominal), and the greatest gross lymph node dimension per each site. LNI pattern (single cells, clusters, micropapillae, small papillae, papillae, glandular, and intraglandular) and the greatest microscopic linear dimension of LNI foci were also recorded. Statistical comparisons between the study and the control group were made using the Fisher exact test and chi test. The log-rank test was used to evaluate the impact of LNI on disease-free survival and overall survival. Clinical follow-up was obtained from the review of medical records and from phone calls to the attending physicians. In terms of general pathologic features, the experimental group had a significantly higher rate of invasive (P=0.01) and noninvasive (P=0.002) implants compared with the control group. In 22% of the cases in the study group, LNI represented the only site of extraovarian disease. The highest yield of lymph nodes with LNI was obtained from pelvic lymph nodes (90%), with a sampling of 3 to 4 sites. The average gross lymph node size range was comparable between the study (0.2 to 4.0 cm) and the control (0.2 to 4.3 cm) groups. The patients in the study group (38.5 y) were on average 10 years younger than those in the control group (49.1 y). Clinical information and follow-up were available for 86% (31) of the cases in both groups. No recurrences were seen in the control group. In the study group, 11% (4) patients are alive with recurrent disease and 6% (2) died of the disease. Histologic diagnosis of recurrences was available in 5 cases and showed low-grade serous carcinoma. Two cases recurred exclusively in the lymph nodes. Although the study group had a higher proportion of patients with disease recurrence and death disease, when the two groups were compared by looking only at FIGO stage III cases, LNI did not have a statistically significant impact on disease-free survival (P=0.09) or the overall survival (P=0.40). There was no relationship between the greatest linear dimension of LNI or the pattern of LNI and disease recurrence. In summary, in cases of OSLMP, LNI is associated with a higher rate of invasive and noninvasive implants, but is not an independent predictor of disease-free survival or overall survival. Women under 40 years of age and with peritoneal implants may be at particular risk for LNI. Lymphadenectomy upstages a significant proportion of patients with LNI, highlighting the need for lymph node sampling in all OSLMP cases. Grossly unremarkable lymph nodes are not at a decreased risk of LNI. The pattern and the greatest linear dimension of LNI foci were not shown to have prognostic significance.