This experiment has been done for considering the effect of four types of commercial probiotics (Bioplus 2B, Primalac, Thepax and Protexin) on gastrointestinal microflora of ostrich chickens during 6 weeks (from third week to eighth week of breeding ostrich chickens). The experiment was done in the form of full random design with 5 treatments and 5 replication. The treatments included (1) 0.04 percent of Bioplus 2B, (2) 0.09 percent of Primalac (3) 0.1 percent of Thepax, (4) 0.03 percent of Protexin (5) without probiotics (control treatment). Data was analyzed by SPSS software and means were compared by Tukey test. The result showed that adding probiotics have significant effect on the microbial population of bacteria of Lactic acid, Escherichia coli and coliforms (p<0.05). Generally amongst different treatments, treatment 1 ( having 0.04 percent of Bioplus 2B and attendance 2 (having 0.09 percent of Primalac) have had the greatest effect on gastrointestinal microflora.