Objective: To investigate the effect of Olibra (TM) fat emulsion on medium-term food intake and appetite in non-obese subjects. Design: Double-blind, placebo-controlled, within-subject crossover. Setting: University of Ulster, Coleraine. Subjects: A total of 28 subjects (14 male, 14 female). Interventions: Subjects were randomly assigned to receive either a 200 g portion of test (5 g of Olibra (TM) fat) or control (5 g milk fat) yoghurt for breakfast for 2 x 3 week `study' phases, separated by a 3-week `wash-out' phase. On days 1, 8 and 22 of the study phases, food intake 4 h post-consumption of the yoghurt was assessed by pre- and post-covert weighing at an ad libitum buffet-style test lunch. Throughout each of these study days, appetite was assessed using visual analogue scales (VAS) at regular intervals. For the remainder of the study days, and the following 24 h ('post-study days'), subjects reported their food intake using weighed dietary records. Results: Consumption of the Olibra (TM) emulsion had no significant effect on mean energy, macronutrient or amounts of food consumed at the lunch 4 h post-consumption. Self-reported food intakes indicated that there was no significant effect of the emulsion on energy intakes for the remainder of each study day and post-study days. There was considerable individual variation in food intakes following consumption of the Olibra (TM) emulsion, with 46, 59 and 57% of subjects reducing their energy intakes at lunch on days 1, 8 and 22. There was no consistent effect of the emulsion on appetite ratings. Conclusions: In contrast to earlier studies, there was no evidence of a short- or medium-term effect of the Olibra (TM) emulsion on food intake or appetite. This could be owing to numerous confounding factors influencing eating behaviour and/or the different study design used in the present study.