M30 and M65 are relatively new assays that detect different circulating forms of the epithelial cell structural protein cytokeratin 18. This study was conducted to investigate the serum levels of M30 and M65 in patients with metastatic pancreatic adenocarcinoma (MPA) and the relationship with tumor progression and known prognostic parameters. Twenty-six patients with MPA were investigated. Serum samples were obtained on first admission before treatment and follow-up. Both serum M30 and M65 levels were determined using enzyme-linked immunosorbent assay. The median age at diagnosis was 59 years, range 32-80 years; 14 patients were men. All patients had metastatic stage, and most (n = 21, 81%) had hepatic metastasis. The baseline levels of both serum M30 and serum M65 were significantly higher in patients with MPA than those in the control group (p < 0.001, for both assays). Serum M65 level was only significantly higher in the patients with elevated serum LDH levels than in others with normal serum LDH levels (p = 0.03). For serum M30 levels, no correlation was found. The significant relationship was found between the serum levels of M30 and M65 (r(s) = 0. 926, n = 26, p < 0.001, Spearman's correlation). The median survival for all patients was 31.7 ± 2.2 weeks (95% CI = 27.31-36.08). Although only the serum LDH level was found to be a significant prognostic factor (p = 0.01), neither serum M30 nor serum M65 had significant effect on survival (p = 0.28 and p = 0.15, respectively). In conclusion, although both serum levels of M30 and M65 assays were found to be of diagnostic value, no predictive and prognostic values were determined in MPA patients.