Background and Οbjective: Considerable overlap exists in the clinical presentation of Post COVID-19 Condition and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). The current study aimed to compare symptoms and patient-reported Quality of Life (QoL) among people with Post COVID-19 Condition and ME/CFS in Australia. Methods: QoL data was collected from n=61 ME/CFS patients, n=31 Post COVID-19 Condition patients, and n=54 Healthy Controls (HCs) via validated instruments. The ME/CFS and Post COVID-19 Condition participants also provided self-reported severity and frequency of symptoms derived from the Canadian and International Consensus Criteria for ME/CFS and the World Health Organization case definition for Post COVID-19 Condition. Study variables were compared with Chi-square, Fisher’s exact, Fisher-Freeman-Halton, Mann-Whitney U, and Kruskal-Wallis H tests using Statistical Package for the Social Sciences version 29. Symptom clusters among the two illness cohorts were identified with hierarchical cluster analysis. Results: ME/CFS was associated with a higher prevalence of short-term memory loss (p=0.039), muscle weakness (p<0.001), lymphadenopathy (p=0.013), and nausea (p=0.003). People with ME/CFS also reported more severe light-headedness (p=0.011) and more frequent unrefreshed sleep (p=0.011), but less frequent heart palpitations (p=0.040). Symptom prevalence, severity, and frequency were otherwise comparable. Few differences existed in the QoL of the two illness cohorts, both of which returned significantly impaired QoL scores when compared with HCs (p<0.001). Cluster analysis of symptom prevalence revealed four clusters: 1) Low gastrointestinal, low neurosensory; 2) Moderate gastrointestinal, low orthostatic and memory loss; 3) Moderate gastrointestinal, high orthostatic and memory loss; and 4) High gastrointestinal, high pain, which did not differ in sociodemographic information, illness status, or diagnostic criteria met. Conclusions: Post COVID-19 Condition and ME/CFS are remarkably similar in presentation and, like ME/CFS, Post COVID-19 Condition has a profound and negative impact on patient QoL. Gastrointestinal symptoms may have a role in determining ME/CFS and Post COVID-19 Condition subtypes.