The question was asked whether kinetics of CA19-9 would serve as a predictor of chemotherapeutic outcome in advanced pancreatic cancer treated with gemcitabine and cisplatin. Twenty one patients, 5 females and 16 males (median age 56 yrs, range 36-71 yrs) suffering from adenocarcinoma of the exocrine pancreas were analysed. Chemotherapy was applied for a median of 6 courses (range 2-21). Four patients achieved a complete remission, four a partial remission (OR = 38%), while stable disease was documented in 8 and progressive disease in 5 patients. Among 4 CR patients, all demonstrated a significant decline of CA 19-9 levels during the initial three treatment courses with apparent half-lifes of 15, 18, 24, and 33 days. At a cut-off level of 37 U/mL, all CR patients reached normal values in the course of treatment. All patients achieving PR showed a decrease of CA 19-9 values at apparent half-lifes of 9, 16, 88 and 89 days. Among patients with stable disease, CA19-9 transiently decreased in 7/8 patients and remained stable in 1 patient. However, values increased later in all patients after a median of 3 treatment courses (range 2-9). In patients with disease progression, CA 19-9 initially increased in 4/5 patients, while a further patient did so only beyound 100 days of treatment. In conclusion, kinetics of CA19-9 serum concentration may serve as an early indicator of response to gemcitabine/cisplatin chemotherapy in advanced pancreatic cancer.