In psychiatric practice, pharmacogenetics has the potential to identify patients with an increased risk of unsatisfactory drug responses. Genotype-guided treatment adjustments may increase benefits and reduce harm in these patients; however, pharmacogenetic testing is not (yet) common practice and more pharmacogenetic research in psychiatric patients is warranted. An important precondition for this type of research is the establishment of biobanks. In this paper, we argue that, for the storage of samples in psychiatric biobanks, waiving of consent is not ethically justifiable since the risks cannot be considered minimal and the argument of impracticability does not apply. An opt-out consent procedure is also not justifiable, since it presumes competence while the decisional competence of psychiatric patients needs to be carefully evaluated. We state that an enhanced opt-in consent procedure is ethically necessary, i.e. a procedure that supports the patients' decision-making at the time when the patient is most competent. Nevertheless, such a procedure is not the traditional exhaustive informed consent procedure, since this is not feasible in the case of biobanking.