Peripheral blood stem cell cryopreservation is associated with cell damage and decreased viability. We evaluated the impact of up to 10 years of cryopreservation (5% DMSO) on viability of CD34+ cells utilizing graft samples of consecutive patients (2002–2012) with different malignancies who underwent stem cell collection and transplantation. Viability of CD34+ cells from oncohaematological patients measured after 5 weeks (97·2 ± 0·6%) or after 9–10 years of cryopreservation (95·9 ± 0·5%) was unaffected. Haemoglobin, granulocyte and platelet recovery after transplantation of long-term cryopreserved grafts occurred within 8–13 days. CD34+ stem cells can be safely stored up to 9–10 years, without affecting cell viability and clinical effectiveness.