This study aims to provide greater insight into the current decision-making process on diagnostic testing for dementia by exploring the expectations, needs and experiences of patients with memory complaints, significant others and general practitioners (GPs). We performed semi-structured interviews with patients (>60years) who consulted their GP on memory complaints, significant others and GPs. Participants were recruited until data saturation was reached in thematic analysis of interview transcripts. We performed 51 interviews (patients n = 20, significant others n = 15, GPs n = 16). Thematic analysis revealed four themes: (i) 'drivers to (not) testing', i.e. need to act on symptoms, beliefs on the necessity and expected outcomes of diagnostic testing; (ii) 'patient preferences and context are critical in the actual decision', i.e. in the actual decision-making process interpretation of symptoms, GPs' desire to meet patient preferences, social context and healthcare system dynamics guided the decision; (iii) 'need for individualised communication in the decision-making process', i.e. for patients feeling heard was a prerequisite for decision-making and GPs tailored communication strategies to individual patients and (iv) 'GP practice and barriers to shared decision-making (SDM)', i.e. although GPs value SDM in the decision on diagnostic testing for dementia, patients express limited awareness of the decision and options at stake. Decision-making on diagnostic testing for dementia is a multifactorial and preference-guided process for all involved stakeholders, but decisions are often not explicitly jointly made. Development of patient decision aids could facilitate better involvement and more informed choices by patients.