The effect of exogenous melatonin (EM) on growth, physiological and haematological parameters of West African dwarf (WAD) bucks was evaluated in the experiment. Intact selected sixteen WAD bucks were distributed into 4 treatment groups of 0, 3, 6 and 9 mg EM. Bucks were orally dozed with EM 3 times per week for 16 weeks. Blood samples were collected at 0th week, 8th week and 16th week of experiment for evaluation of haematological parameters. Analysis of Variance was carried out and significant means were separated using SAS. Results showed bucks given 6 mg EM had higher average daily weight gain of 31.3 g compared with others. Feed and water intake were similar across treatments, but feed conversion ratio was significantly lower in bucks given 6 mg EM. Values recorded in the morning of data collection days showed pulse and respiratory rates to be significantly different, with bucks given 6 mg of EM having lowest values.  6 mg group was also different for packed cell volume (32.57%), haemoglobin (10.72g/dl), red blood cell (11.38 1012 /L), neutrophil (35.50%) and lymphocyte (64.30%). Therefore, dose of 6 mg/animal EM influences growth performance, physiological and haematological parameters of WAD bucks positively and is therefore recommended for WAD bucks for optimal performance.