We conducted a pilot study for a quantitative survey among chronically ill adolescents and their parents. Our main objectives were to assess the use of an online questionnaire to collect data on the transition process from pediatric to an adult care and to evaluate the willingness to answer in our target population. A total of 183 adolescents and their parents were contacted by sending them three postal letters (an invitation to participate and two reminders about 3 and 9 weeks after the invitation). Before the second reminder, we only offered the option to use an online questionnaire, and the response rate stayed very low, only slightly above 10%. With the second reminder, we offered the alternative to answer using a paper-and-pencil questionnaire, and we also gave all participants a gift-card of small value, unconditionally to the completion of the questionnaire. Following the mailing of this second reminder letter, the response rate almost doubled in a few days, and we ended up with more than 35% of answers, from both the adolescents and the parents. We learned from this pilot study that health data are at least as difficult to collect as any other data and that chronically ill adolescents are as difficult to survey as healthy adolescents, even when the subject of the study concerns the participants directly. Chronically ill adolescents and their parents can be reluctant to send information regarding their health on the Internet, so the option of answering using a paper-and-pencil questionnaire can be very much appreciated. Moreover, giving a small gift-card to all participants also helps increasing the number of answers.