BackgroundGiven the inevitable relentless progressing nature of amyotrophic lateral sclerosis (ALS), it is essential to identify factors influencing patients’ wellbeing. The study aimed to prospectively assess factors influencing the quality of life (QoL) and depression in ALS patients compared to healthy controls (HCs) from Poland, Germany and Sweden and their relationship to socio-demographic and clinical factors.Methods314 ALS patients (120 from Poland, 140 from Germany, 54 from Sweden) and 311 age-, sex- and education-level-matched HCs underwent standardized interviews for quality of life, depression, functional status and pain.ResultsPatients from all three countries showed similar levels of functional impairment (ALSFRS-R). Overall, ALS patients assessed their quality of life as lower compared to HCs (p < 0.001 for the anamnestic comparative self-assessment (ACSA), p = 0.002 for the Schedule for the evaluation of the subjective quality of life - SEIQoL- direct weighting (SEIQoL-DW). Also, the German and Swedish patients, but not the Polish, reported higher depression levels than the corresponding HCs (p < 0.001). Analysis of ALS groups revealed that functional impairment was related to a lower quality of life (ACSA) and higher depression levels among German ALS patients. Longer time since diagnosis predicted lower depression and (in male subjects) higher quality of life.ConclusionsALS patients assess their quality of life and mood lower than healthy individuals within the studied countries. The relationships between clinical and demographic factors are moderated by country of provenance, which bears implications for the design and interpretation of scientific and clinical studies, which should reflect the complexity and heterogeneity of mechanisms determining QoL.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12904-023-01189-2.