Physical health can be measured in several ways both based on subjective experiences and with objective tools. However, mental health can only be measured through subjective experiences and sensations, which can be biased. Therefore, researchers adopted the notion of an objective tool to assess well-being as a complement to existing self-reported scales and suggested that heart rate variability (HRV) might be an indicator of well-being. Hence, this thesis investigates the relationship between subjective well-being (SWB) and HRV, particularly high frequency-HRV (HF-HRV). Three hypotheses, which included different forms of well-being, were developed to test the relationship. And the hypotheses were: Cognitive well-being correlates positively with HF-HRV. Positive affect correlates positively with HF-HRV, and negative affect correlates negatively with HF-HRV. A total of 19 healthy Swedish females aged from 20-35 participated and answered questionnaires measuring SWB. After they completed the SWB-scales, their heart rate was measured and then converted into HF-HRV data. The findings revealed no correlations between the cognitive SWB and HF-HRV, neither to affective SWB.