A series of thin sections from a Mesolithic hearth pit from the site of Soest-Staringlaan (the Netherlands) were studied to assess the variability of the charred and non-charred organic remains inside them. Non-charred remains included plant roots; fungal fruiting bodies and hyphae; mesofauna coprolites; and podzolization-related polymorphic humus and monomorphic humus coatings. Charred remains included charcoal of coniferous wood, charred non-woody plant material and fragments of wood. However, a large proportion of the charred material consists of fine, powdery fragments. This may at least partly be due to trampling and/or eluviation of disintegrating charcoal. Most of the micromorphological features in the Soest pit are similar to those found in pits from previously investigated Mesolithic sites. Common features include the presence of large fragments of charcoal in the lower parts of hearth pits, tar, charred humus and evidence for charcoal disintegration and eluviation. The combined results first and foremost demonstrate the strong variability between samples within the same feature. This implies that multiple samples from a pit are necessary in order to at least attempt to try to capture this variability. It is also clear from the results that sampling should include layers or deposits that macroscopically seem to be outside the feature proper. These may contain parts of the phenomenon studied that are difficult to recognize with the naked eye. These observations add to the notion that Mesolithic hearth pits are generally formed by the same human activities, formation processes and taphonomy. However, they make clear that intense sampling is needed for any research to better understand the formation of these pits and that supplemental chemical analyses may be needed to better interpret the observed features and get a better idea of the potential use of these common Mesolithic features.