Purpose Survivors of critical illness often suffer from reduced health-related quality of life (HRQoL) due to long-term physical, cognitive, and mental health problems, also known as post-intensive care syndrome (PICS). Some intensive care unit (ICU) survivors even consider their state of health unacceptable. The aim of this study was to investigate the determinants of self-reported unacceptable outcome of ICU treatment. Methods Patients who were admitted to the ICU for at least 48 h and survived the first year after discharge completed validated questionnaires on overall HRQoL and the components of PICS and stated whether they considered their current state of health an acceptable outcome of ICU treatment. The effects of overall HRQoL and components of PICS on unacceptable outcome were studied using multiple logistic regression analysis. Results Of 1453 patients, 67 (5%) reported their health state an unacceptable outcome of ICU treatment. These patients had a lower score on overall HRQoL (EQ-5D-index value of 0.57 vs. 0.81; p < 0.001), but we could not determine a cutoff value of the EQ-5D-index value that reliably identified unacceptable outcome. In the multivariate analysis, only the hospital anxiety and depression scale was significantly associated with an unacceptable outcome (OR 2.06, 99% CI 1.18–3.61). Conclusions Although there is a strong association between low overall HRQoL and self-reported unacceptable outcome of ICU treatment, patients with low overall HRQoL may still consider their outcome acceptable. The mental component of PICS, but not the physical and cognitive component, is strongly associated with self-reported unacceptable outcome. Electronic supplementary material The online version of this article (10.1007/s00134-019-05583-4) contains supplementary material, which is available to authorized users.