Silver nanoparticles (Ag NPs) can affect female fertility because they can cause toxicity in the ovaries. The aim of this study is to see if Spirulina platensis (SP) can protect mouse from Ag NPs-exposed toxicity in its ovary. Twenty-four female Naval Medical Research Institute (NMRI) mice were divided into four groups (n = 6 per group): control; Ag NPs (500 mg/kg daily); SP (300 mg/kg daily) and Ag NPs + SP (With the same defined doses). 30 days after oral gavage treatment, biochemical parameters were measured and ovary compartments were estimated stereologically. The Ferric Reducing Antioxidant Power (FRAP) values, hormonal concentrations, corpus luteum volume, and the number of healthy follicles were all significantly lower (p<0.05) in the Ag NPs group compared with the control group. in the SP group, malondialdehyde concentration and atretic follicles were significantly lower (p<0.05) compared with the control group. There was no significant difference in the mean total volume of ovary, cortex, medulla, oocyte and its nucleus, and the thickness of the zona pellucida in any group. Although, SP in the Ag NPs + SP group cannot compensate the above parameters to the control level, it considerably improves ovarian damage caused by Ag NPs through reducing oxidative stress.