This study investigated the amount and proportion of unrecognized fluorinated organic chemicals in humans and assessed exposure to these chemicals for two study days (T1 and T2 with 2 to 3 weeks apart) using the extractable organofluorine (EOF) and mass balance of EOF approaches. Samples were provided by the Norwegian Institute of Public Health (NIPH), Norway, through the EU project 'European Test and Risk Assessment Strategies for Mixtures' (EuroMix, 633172-2) and were collected from individuals living in the counties of Oslo and Akershus in Norway between September 2016 and November 2017. In the EuroMix study, a total of 143 subjects were studied at T1. Of these, 72 subjects were also studied at T2, forming a paired sample. In this specific investigation, samples from the EuroMix-study (Cohort 1) were used to examine how dietary habits and use of personal care products influence the proportion of unrecognized EOF in the blood. In a separate cohort, the potential contribution of fluorinated pharmaceutical (fluoxetine) to unrecognized fluorinated chemicals in humans was studied (Cohort 2). Results from Cohort 1 showed that up to 81% of the EOF was unrecognized (median 38%), and the amount of unrecognized EOF varied between individuals. In 36% of the paired samples collected 2 to 3 weeks apart, the EOF concentrations changed by more than 25%. No dietary habits or use of personal care products were associated with the proportion of unrecognized EOF in samples from T1. The proportion of unrecognized EOF in samples from T2 were associated with consumption of Potato/vegetables. Trifluoroacetic acid (TFA) was the dominant fluorinated organic chemical in the samples, with concentrations approximately twice that of PFOS. The use of fluorinated pharmaceuticals in Cohort 2 was associated with increased concentrations of both unrecognized EOF and TFA in the blood. The presence and concentrations of TFA and unrecognized EOF observed in this study warrants further investigation into its sources.