Post-COVID syndrome (PCS) is characterized by a variety of non-specific symptoms. One of the leading symptoms is fatigue. So far, there is no evidence-based causal therapy established and treatment of PCS is primarily symptom-oriented. The Clinic for Internal and Integrative Medicine in Bamberg, Germany, offers a comprehensive multimodal integrative inpatient therapy for PCS patients. Within a prospective uncontrolled observational study, the results of N = 79 patients were analysed. Post-COVID fatigue patients were hospitalized for up to 14 days. The treatment consists of individual modules depending on the patient's needs. It includes a wide range of integrative non-pharmacological treatment modalities. Outcomes were assessed before and after the inpatient treatment as well as 6 months after discharge from the hospital. Results show that fatigue of post-COVID patients in this study (M = 76.30, SD = 10.18, N = 64) was initially significantly higher than in the subsample "women aged 60-92years" of the general German population (M = 51.5, Schwarz et al. [Schwarz et al. in Onkologie 26:140-144, 2003]; T(63) = 19.50, p < .001). Fatigue was significantly and clinically relevant reduced directly after discharge (MT1 = 76.21, SD = 11.38, N = 42; MT2 = 66.57, SD = 15.55, N = 42), F(1, 41) = 19.80, p < .001, partial eta squared = .326, as well as six months after discharge (MT3 = 65.31, SD = 17.20, N = 42), F(1, 41), p < .001, partial eta squared = .371. Additionally, self-reported ability to work (NRS, 0-10) improved significantly from admission (MT1 = 2.54, SD = 2.23, N = 39) to discharge (MT2 = 4.26, SD = 2.60, N = 39), F(1, 38) = 26.37, p < .001, partial eta squared = .410), as well as to six months later (MT3 = 4.41, SD = 3.23, N = 39), F(1, 38) = 15.00, p < .001, partial eta squared = .283. The study showed that patients suffering from chronic post-COVID syndrome for several months can achieve a significant improvement in their leading fatigue symptoms and a significant improvement in the subjective assessment of their ability to work through a comprehensive two-week multimodal integrative inpatient program.