Introduction:  Data on the incidence and causes of late (>100 d) non‐relapse mortality (NRM) in autologous stem cell transplant (ASCT) recipients is limited.

Patients and methods:  We have analysed NRM in a cohort of 1482 adult patients who received ASCT in 1990–2003 in six Finnish transplant centres. The most common diagnoses included non‐Hodgkin's lymphoma (NHL) (n = 542), multiple myeloma (MM) (n = 528), breast cancer (n = 132); Hodgkin's lymphoma (HL) (n = 86) and chronic lymphocytic leukaemia (CLL) (n = 63).

Results:  Until September 2005, 646 patients (44%) have died. Late NRM was observed in 68 patients (4.6% of ASCT recipients; 11% of all deaths). There were 38 males and 30 females with a median age of 58 yr (20–69) at the time of ASCT. The median time to NRM was 27 months from ASCT (3–112). The risk of NRM was highest in patients with CLL (9.5%) and those with HL (8.1%) followed by MM and NHL (4.9% and 4.8%, respectively). The risk of late NRM was comparable in patients who received total body irradiation (TBI) and those who received chemotherapy‐only regimens (6.7% vs. 4.3%). Another malignancy was the most common cause of late NRM (24 patients, 35% of late NRM). Twelve patients (0.8% of ASCT recipients) have died due to secondary haematological malignancy. Altogether 22 patients (32% of late NRM) died from infectious causes.

Conclusions:  Malignancies and late infections are important causes of NRM after ASCT. These facts point out the importance of prolonged follow‐up in ASCT recipients.