Healthy volunteers who participated in an experiment were asked to complete a questionnaire about their experiences. Special attention was paid to their motives and the informed consent procedure. The motives of healthy volunteers for participating in a study differed according to age. Young volunteers mostly participated because of the financial compensation, while older volunteers mainly participated to get a medical check-up, which was part of the selection procedure, or because of the benefit that other people might obtain from the results of the experiment. In most experiments the volunteers were content with the information given about the experiment, which was provided orally and in a hand-out. The information procedure was crucial for the experiment, because optimum information was of the utmost importance in keeping the volunteers motivated during the experiment. Another conclusion was that the researcher should not be afraid that too much information was given. Adequate information was also important in recruiting new volunteers, because they mostly become interested because of information obtained from their predecessors. A personal approach towards the volunteers during the experiment was appreciated by them and was an important help in keeping the volunteers motivated during the experiment.