This study was designed to investigate reproductive performance of adult New Zealand White (NZW) rabbit bucks as affected by oral administration of Spirulina platensis (S. platensis). Bucks were randomly distributed into 2 homogeneous groups (10 in each). The first group were orally received 3 ml distilled water (control), while those in the second group were orally treated with 3 ml distilled water containing S. platensis at a level of 700 mg/buck as daily oral for 5 weeks before semen collection period. Semen was collected twice weekly for 10 successive weeks by artificial vagina. On day of semen collection, reaction time (RT) and physical semen characteristics were determined. During the last week of collection, concentration of testosterone in blood serum (STC), and some biochemicals and antioxidant activity in seminal plasma were estimated. Results showed that the S. platensis orally administration bucks improved (P<0.01) LBW, testicular (P<0.001) and epididymal (P<0.01) weights, testicular length (P<0.01) and STC (P<0.001), and decreased RT (P<0.01) of bucks as compared to controls. Ejaculate volume and percentages of progressive sperm motility, livability, normality, and acrosomal damage as well as sperm cell concentration and total sperm output (motile, motile normal, motile live and total functional) significantly improved by S. platensis compared with controls. Also, semen pH value decreased (P<0.05) by S. platensis treatment. Concentrations of total fructose and total proteins were significantly higher in seminal plasma as affected by S. platensis treatment, while, concentrations of albumin (AL), globulin (GL) and AL: GL ratio were not affected by S. platensis treatment. Activity of total antioxidant capacity, glutathione S-transferase, superoxide dismutase, and glutathione peroxidase significantly increased, while TBARS concentration significantly decreased in seminal plasma of bucks treated with S. platensis, however, glutathione concentration was not affected. Conception rate and kindling rate, litter size and average bunny weight at birth improved in doe rabbits mated with bucks treated with S. platensis. In conclusion,S. platensis at a level of 700 mg/buck as oral administration for 5 weeks period to be used in natural mating or artificial insemination is recommended to be serving as a supportive treatment in the nutritional management to improve semen production of rabbit bucks, and fertility of doe rabbits mated with these bucks.