_____________________________________________________________________________________________________ *Corresponding author: E-mail: drchiobinna@yahoo.co.uk, victoria_obinna@uniport.edu.ng; Journal of Scientific Research & Reports 25(4): 1-7, 2019; Article no.JSRR.53017 ISSN: 2320-0227 Haematological Effect of Toluene in Wistar Rats Victoria C. Obinna 1* and Gabriel O. Agu 1 1 Department of Animal and Environmental Biology, Faculty of Science, University of Port Harcourt, Rivers State, Nigeria. Authors’ contributions This work was carried out in collaboration between both authors. Both authors read and approved the final manuscript. Article Information DOI: 10.9734/JSRR/2019/v25i4301932 Editor(s): (1) Dr. Karl Kingsley, University of Nevada, Las Vegas - School of Dental Medicine, USA. Reviewers: (1) Dharma Lindarto, University of North Sumatra, Indonesia. (2) Jurandyr Santos Nogueira, Federal University of Bahia Ondina Campus, Brazil. (3) Aba, Patrick Emeka, Nigeria. Complete Peer review History: http://www.sdiarticle4.com/review-history/53017 Received 01 October 2019 Accepted 05 December 2019 Published 11 December 2019 ABSTRACT Toxicity of toluene arising from solvent abuse, occupation hazards and environmental pollution has generated a lot of concern in recent times. Young people are getting more involved in the abuse of toluene by deliberate inhalation of toluene-containing substances which may result in high level of exposure to toluene. This abuse may have adverse effect on their health. This study was therefore designed to investigate the effect of oral exposure to toluene on haematological parameters using male albino rats as model. Twenty animals were randomly assigned to 4 groups of 5 rats each. Group A (Control) received 0.5 ml of olive oil (vehicle) while groups B, C and D received 31.8, 63.6 and 127.2 mg/kg respectively of toluene for 21 days by oral gavage. At the end of the treatments, the animals were anaesthetized and blood samples were collected for haematological investigations. No significant (p >0.05) variation occurred in the mean values of PCV, haemoglobin concentration, RBC and platelet counts in comparison with the control. There was a significant (p <0.05) increase in total WBC and lymphocyte counts with a higher increase (p<0.01) in total neutrophil count. No significant (p >0.05) change in the total monocyte and eosinophil counts relative to the control. Oral administration of toluene as used in this study may be toxic to health depending on the dose and duration of exposure. Keywords: Blood; solvent abuse; toluene; toxicity. Original Research Article