Pesticides are commonly used compounds in agriculture. Especially, organophosphates (OPs) are among the extensively used pesticides. Therefore, OPs poisoning is common, especially in underdeveloped and developing countries. Primary aim of this study was to research the effects of acute OPs poisoning on genome instability in the individuals' lymphocytes with acute OPs poisoning both by using the cytokinesis-block micronucleus cytome (CBMN-cyt) assay to examine chromosome/genome damage, cell proliferation index and cell death rate and by using the plasma 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels to determine oxidative DNA damage. Secondary aim of this study was also to assess whether a relation exists between endocrine hormones and the genome damage in acute OPs poisoning. In the study, blood samples were analysed of 13 patients before and after treatment admitted to the Department of Intensive Care Unit with acute OPs poisoning and of 13 healthy subjects of similar age and sex. The present study demonstrates that genome damage (micronucleus; MN and nucleoplasmic bridges; NPBs frequencies), apoptotic and necrotic cell frequencies increased in lymphocytes of patients with acute OPs poisoning before treatment and decreased after treatment. The present study also show that CBMN cyt assay parameters and 8-OHdG levels could be affected by some endocrine hormones such as E2, fT3, fT4, GH, IGF-1, FSH, LH, TSH, PRL, but not be related to ACTH and tT levels in acute OPs poisoning. In conclusion, it is believed that this is the first study to evaluate the chromosomal/oxidative DNA damage, cell proliferation, cell death and their associations with endocrine hormones in acute OPs poisoning. These preliminary findings need to be supported by further studies with larger sample sizes.