The paper describes the follow-up survey of the PinK study 'Paare in Kinderwunschbehandlung' (couples undergoing fertility treatment). This interdisciplinary study aims at a broader and better understanding of the situation of couples with an unfulfilled desire to have a child. The focus in the follow-up survey is on the situation of the couples one year after their first visit to a fertility clinic in Rhineland-Palatinate or in the capital of Hesse, Wiesbaden. Approximately one year after the baseline survey, self-administered questionnaires were sent to respondents who had signed a written agreement to remain in the study. The field period lasted from June 2013 to August 2014. The final sample consists of 140 women and 93 men. In 89 couples both partners participated. The longitudinal data set includes 224 respondents. The share of baseline survey participants who also participated in the follow-up is 39.6 %. This report describes the study design and materials for the follow-up as well as the sample and analyses the selectivity of dropouts from the baseline sample.