Metalaxyl is a benzenoid fungicide used to control fungal diseases. The aim of this work is to investigate the effect of metalaxyl on haematological and biochemical parameters in male albino mice. In this study, animals were divided into two groups. The animals in the first group (20 mice) were given metalaxyl orally through a stomach tube at a dosage of 1/10 of the LD50 (which was equivalent to 130 mg/kg body weight) at a rate of three times per week for 4 continuous weeks. The second group was treated as a control in which the animals (20 mice) were given water orally. Treating mice with metalaxyl for 2 and 4 weeks induced a significant decrease in the RBC count (5.2±0.24), haemoglobin content (11.5±2.3) and the number of blood platelets (543±15.3). In contrast, metalaxyl treatment induced a significant increase in the WBC count (5.8±0.4). Serum triglyceride and cholesterol levels also increased while total protein and albumin levels decreased in the treated animals. Additionally, metalaxyl treatment resulted in a significant increase in the levels of transaminases, ALT and AST enzymes. The data also revealed a significant increase in serum creatinine in response to metalaxyl toxicity, which might be due to impaired kidney function resulting from fungicide exposure. It was concluded that these metalaxyl effects could be attributed to fungicide-induced oxidative stress, which in turn leads to signs of toxicity. This result was confirmed by other authors who obtained similar results by observing the effects of some fungicides. The premise of this study was that fungicides must be examined for their possible adverse effects on animals and humans before their application to agricultural fields.