Background and objective Self-care strategies in heart failure (HF) are effective for disease management, yet adherence in many patients is inadequate. Reasons are presumably multifactorial but remain insufficiently investigated; thus, we aimed to analyse self-care adherence and associated factors in outpatients with HF. Methods and results To measure self-care levels and explore barriers and facilitators to self-care adherence in patients with HF, quantitative study using the European Self-Care Behaviour Scale (EHFScBS-9) (n = 80; NYHA II-III, mean age 72 ± 10 years, 58% male) and qualitative study using semi-structured interviews (n = 32; NYHA II-III, mean age 73 ± 11, 63% male) were conducted. We detected lowest adherence to regular exercise (39%) and contacts with healthcare provider in case of worsening symptoms (47%), whereas adherence was highest for regular medication taking (94%). Using the EHFScBS-9 standardized cut-off score ≤ 70, 51% of patients reported inadequate self-care. Binary logistic regression analysis showed significant influence of education (OR = 0.314, 95% CI: 0.103-0.959) and perceived control (OR = 1.236, 95% CI: 1.043-1.465) on self-care adequacy. According to the situation-specific theory of HF self-care, most commonly reported factors affecting the process of self-care were knowledge about HF self-care behaviours (84%), experience with healthcare professionals (84%), beliefs about their expertise (69%) and habits related to medication taking (72%). Among values, working responsibilities (53%) and maintenance of traditions (31%) appeared as the most prevalent socially based values affecting motivation for selfcare. Situational characteristics related to the person (self-confidence, 53%; adaptive coping strategies, 88%), problem (burdensome breathing difficulties, 56%; co-morbidities, 81%) and environment (practical support from family/caregivers, 59%; financial difficulties, 50%) were also commonly reported. Conclusions Various factors, including health-related beliefs, habits and socially based values, need to be taken into account when planning self-care interventions in patients with HF. A patient tailored approach should be based on adequate patient evaluation, taking into consideration the particular personal and social context.