The present study was carried out to clarify the effect of Foot and Mouth Disease Virus (FMDV) on cattle of different ages with references to studying the hematological parameters, biochemical aspects and cardiac biomarkers after accurate diagnosis of FMDV by reverse transcription-polymerase chain reaction (RT-PCR). Forty-five native breed Egyptian female non pregnant cattle (1-5 years old) were divided into two main groups. Group (1): 15 apparently healthy cattle as control group. This group includes animals at age 1-1.5 year (gp.1a), 2-3 years (gp.1b) and 4-5 years (gp.1c). Group (2): 30 infected cattle with the same age category as the control group (gp. 2a, gp. 2b and gp.2c) were collected from different localities in port- Said Governorate, Egypt during  2016-2017 FMD outbreak. Saliva and vesicular fluid from infected cattle were obtained for RT-PCR and blood samples for hematological and biochemical parameters estimation. The infected cattle showed fever, ropy salivation, vesicular eruptions on buccal mucosa and interdigital space. All the identified viruses were FMDV of serotype ‘O' which is circulating among cows of different ages in Egypt. Biochemical results revealed a significant decrease in serum total proteins, albumin, globulins and calcium levels, with a significant increase in serum enzyme activities ALP, GGT, AST and serum levels of urea, creatinine, inorganic phosphrous, malonadiadehyde, nitric oxide, Interleukein10 (IL-10), cardiac tropinine I (cTn I) and creatine kinase MB (CK-MB) concentration. It was concluded thatFMDV significantly affects the hematological and biochemical parameters of infected cattle, especially young one. The detection of cTnI is a very sensitive method for determining myocardial cell damage in the earlier stages of the disease. Moreover, RT-PCR is diagnostic biomarkers for FMD viral infection.