The present study was undertaken to pinpoint the possible protective effect of curcumin against subacute toxicity of Diazinon (DZN) induced adverse effect on some biochemical and cytogenetical parameters. 36 male albino rats were classified randomly into six equal groups. Group (G1) was kept as negative control, G2 and G3 were administrated a high and low dose of DZN as 35 and 17.5 mg/kg b.w. over period of 28 days (5 days/week), respectively. G4 received curcumin as 200 mg/kg diet. G5 and G6 were administrated high and low dose of DZN, respectively and co-treated with curcumin. The obtained results revealed that there was a significant increase in liver and kideny function parameters with significant decline in total protein, albumin, beta and gamma globulins together with albumin/globulins ratio (A/G) of G2 and G3 than control. Also, a significant increase in serum tumor necrosis factor-α (TNF-α), liver, kidney and spleen malondialdehyde (MDA), catalase, nitric oxide (NO) with decrease in total antioxidant capacity (TAC) and glutathione (GSH) levels in G2 and G3than control. Moreover, upturn in level of liver and kidney function was observed in G5 and G6. As curcumin is antioxidant and has anti-inflammatory effect could rebalance the state of hypoprotenmia associated with hypoalbunemia, and attenuates the oxidative indices and TNF-α induced by DZN. A significant increase in the percentage of micronucleated polychromatic erythrocytes (MPCE), and significant decrease in normohromatic erythrocytes (NCE) in G2 and G3 than control, whiles the ratio of (PCE/NCE) increase only in G2 than control. On the other hand, co administration of curcumin mixed with diet in case of high and low dose of DZN group's cause a significant decrease in (MPCE), and increase of (NCE) in G5 and G6 in comparing to G2 and G3, while (PCE/NCE) decrease insignificant in G5 and G6 compared to G2 and G3. Histophathological examination revealed degenerative changes in the liver and kidney tissues in G2 and G3. Meanwhile, curcumin alivate this changes in G5 and G6. These results indicated that curcumin may be able to meliorate the worst biochemical and cytogentical alterations caused by high and low doses of diazinon.