Fast, accurate and thorough assessments of meiofaunal communities are crucial requirements for ecological studies and routine monitoring of ecosystem status. This study scrutinizes the reliability of the molecular approach through a comparison of morphological and molecular inventories of meiofaunal diversity, with a special focus on nematodes. Sediment samples were collected from a reference coastal Mediterranean site. Metabarcoding analysis was performed using a nuclear marker (small subunit 18S ribosomal RNA) and compared to a morphological analysis performed on the same sample-cores. The results from morphological and molecular inventories differed but were complementary. The molecular analysis revealed a remarkable level of diversity (16 phyla) that exceeded the traditional morphological analysis (10 phyla), showing that meiofaunal diversity can greatly exceed current perceptions. The molecular method proved powerful in detecting the presence of soft-bodied predators, such as Platyhelminthes, possibly reflecting preservation bias in morphological approaches. Even if the molecular inventory identified 57.5% of the sampled diversity, surprisingly, it has not revealed the presence of some nematode genera identified through morphological assessment. While the technique is promising, some further developments are required. As the dominant genus Sabatieria was undetected by the molecular approach, despite being present in the Silva database, improving the knowledge of specific primers should be a priority. Additionally, with 77% of nematode OTUs remaining unassigned at genera level, remedy this lower efficiency requires further investigations to provide DNA-sequences of all morphologically identified species.