Background: Unregulated mining has the potential to release harmful substances into the soil, air, and water and this may be associated with negative health, social and environmental impacts. Inhalable dust is produced during processing, grading and during the transit by the vehicles. Epidemiologic data indicate that there are occupational hazards associated with stone crushing and inhalation of stone dust. Quarrying/stone crushing is increasingly becoming the main stay of Ebonyi State economy and major source of internally generated revenue yet there is little or no government policy on regulation and occupational safety. Aim: This study examined the effect of long time exposure to quarry dust on the Full Blood Count (FBC) of quarry workers at Okposi Umuoghara, Ezza LGA of Ebonyi State – Nigeria. Methods: Cross-sectional, descriptive and analytical study was carried out on 100 quarry workers; 36 males and 54 females (age; between 18-57 years) who were exposed to stone dust for more than one year and 84 age/sex matched workers not exposed to quarry dust as control. The haemoglobin concentration, haematocrit, total while blood cell and differential counts were estimated using standard methods. Results: Majority of the quarry workers in Okposi - Umuoghara Idustrial Estate were female, low income and uneducated who are not aware of the health implications of their carrier. There were significant differences in mean values of in Hb, PCV, and total WBC, relative netrophils, lymphocytes and eosinophil counts compared with control. The differential lymphocytes and eosinophil increased significantly (p > 0.05), while the Hb, PCV, total WBC and relative neutrophil count decreased significantly (P < 0.05). No significant variation in differential monocyte count was observed. Conclusion: The alterations in level of some haemotological parameters in exposed workers is an indication of effect of quarry dust on pathopysiology of blood and reticuloendothelia system of factory workers and in general human health. There is need for regular health evaluation of workers and education on the essential safety precautions through the use of personal protective equipment and more mechanized and safer means of stone processing.