The monitoring value of three tumor markers--CA-125, lipid-associated sialic acid (LSA), and NB/70K--alone and in combination has been studied in 152 patients with invasive, epithelial ovarian cancer. The sensitivity and specificity of CA-125 (90 and 92%, respectively) were superior to those of LSA (79 and 63%, respectively) and NB/70K (76 and 74%, respectively). CA-125 by itself showed equal or higher sensitivity as well as higher specificity than in combinations with either LSA or NB/70K. CA-125 predicted cancer at second-look in 87% of cases as did LSA and NB/70K in 70 and 57%, respectively. In patients with negative second-look, CA-125 predicted the disease status in 93% as did LSA and NB/70K in 54 and 63%, respectively. On the basis of these data, the value of simultaneous determination of LSA and NB/70K, in addition to the clinically established CA-125, seems to be limited. This is due mainly to the lack of specificity of LSA and NB/70K. However, the sensitivity and specificity of CA-125 in this study were in the upper reported range.