Some problems of the human health which could be related to the mineralogy, chemistry and morphology of the lignite fly ash from the Ptolemais basin (Greece) are discussed and considered. The Ptolemais lignite fly ash contains 0.8% organic matter and at least 3-4% unburnt lignite. It consists of irregularly shaped, oval and spherical particles, ranging in size from smaller (<5μm) to larger ones. Anhydrite, lime, calcite, gehlenite and quartz account for atleast 80% of the mineral matter, while CaO, SiO₂, Al₂O₃, Fe₂O₃ and S make up almost 85% of the fly ash. W, Cr and Ni are enriched compared to the elements crustal abundances. The main concern here, relates to human genotoxicity and cytotoxicity. Toxicological reactions, pneumoconiosis, mutagenic and carcinogenic effects on human health could be ascribed both to inorganic and organic compounds of the fly ash.