Objective: To investigate the effects of two kinds of decaffeinated coffee on serum lipid profiles in healthy young adults. Design: Randomized controlled study with three study groups and a parallel design, consisting of two consecutive periods. Setting: Outpatient clinical research center in a university clinic. Subjects: 119 healthy students (60 male, 59 female) who were selected after a screening. All completed the study. Blood samples of three subjects (1 male, 2 female) were excluded from evaluation due to later diagnosed genetic anomalies of lipid metabolism. Interventions: All subjects consumed 750-1000 ml of caffeinated filtered coffee per day for a 2 week wash-in period. During the 6 week test period one group continued drinking the caffeinated coffee, while the two other groups consumed different kinds of decaffeinated coffee. Results: Consumption of both types of decaffeinated coffee did not lead to any significant changes in serum total and LDL cholesterol, triglycerides and apolipoprotein B. Furthermore, there were no significant differences in the reactions between the three groups. The diet did not change during the study. Conclusions: Switch from regular to decaffeinated coffee had no cholesterol-elevating effects, irrespective of the type of coffee. Sponsorship: Institute tor Scientific Information on Coffee, Paris.