This is a Phase I, double-blind, double-dummy, randomized, placebo- and active-controlled, 4-period crossover trial. This means the study doctor nor yourself know in which treatment session you will receive which active medication or matching placebo. Every participant will receive each treatment in turn. The order in which you receive the treatment sessions is determined by chance, like tossing a coin. The purpose of the study is to evaluate the effect of telaprevir (TVR) on the results of electrocardiograms (electric recording of the heart). Two dose regimens of TVR will be tested, i.e. 750 mg every 8 hours (the dose that will be given to patients) and 1875 mg every 8 hours (a dose higher than the one that will be given to patients), administered for 4 days, with an additional morning dose on Day 5. A single dose of 400 mg moxifloxacin will be used as a positive control to assess trial sensitivity. The trial population will consist of 44 healthy volunteers. Treatment A will consist of TVR 750 mg every 8 hours on Days 1-4 + single 750 mg morning dose on Day 5 (2 active TVR tablets + 3 TVR placebo tablets every 8 hours on Days 1 to 4 with a single morning dose on Day 5, and a single morning dose of moxifloxacin placebo on Day 5). Treatment B will consist of TVR 1875 mg every 8 hours on Days 1 to 4 + single 1875 mg morning dose on Day 5 (5 active TVR tablets every 8 hours on Days 1 to 4 with a single morning dose on Day 5, and a single morning dose of moxifloxacin placebo on Day 5). Treatment C will consist of a single dose of 400 mg moxifloxacin (5 TVR placebo tablets every 8 hours on Days 1 to 4 with a single morning dose on Day 5, and a single morning dose of active moxifloxacin on Day 5). Treatment D will consist of placebo (5 TVR placebo tablets every 8 hours on Days 1 to 4 with a single morning dose on Day 5, and a single morning dose of moxifloxacin placebo on Day 5).There will be a washout period of 8 days between subsequent treatment sessions. Electrocardiograms (ECGs) will be recorded continuously for 24 hours by Holter monitoring (small electrodes will be attached to your chest and connected to a small device to record your heart rhythm over a 24-hour period) on the day before intake of study medication starts and on Day 5 of all treatment sessions. In addition, for safety monitoring, separate ECGs will be performed at predefined time points. Samples to access pharmacokinetics (how the drug is absorbed into the bloodstream, distributed in the body and eliminated from the body) of TVR and moxifloxacin will be collected on the day before intake of medication starts and day 5 of all treatment sessions, as well as predose on Days 2, 3 and 4 of all treatment sessions. Safety and tolerability will be evaluated throughout the trial by evaluating results of blood- and urine analysis, vital signs, physical examinations, alcohol breath tests and by assessing how you are feeling. In every treatment session, participants will receive 5 oral tablets of 375 mg TVR or placebo every 8 hours on Days 1 to 4 with a single morning dose on Day 5, and a single oral morning dose of 400 mg moxifloxacin or placebo on Day 5. In between treatment sessions, there will be a wash-out period of 8 days.