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We used egg breakโout and spermatozoa trapped in the perivitelline layer of eggs to test the hypothesis that sperm supply and egg fertilization rate are high in the ostrich. Egg fertilization status was determined at breakโout by the appearance of the germinal disc (GD) and then the perivitelline layer overlying the GD region was collected to count sperm (Sperm~OPVL~) under fluorescence following staining with 4โฒ,6โฒโdiamidinoโ2โphenyindole (DAPI). The study was carried out on commercial ostrich farms over two laying seasons. In the first year, 229 eggs from nine randomly chosen ostrich pens comprising pairs, trios (two females, one male) and larger groups were collected for 1โweek of every month of laying. Eggs contained 253โยฑโ18 Sperm~OPVL~/mm^2^ of the GD (meanโยฑโSEM; range 0โ1330). Egg fertilization rate averaged 89.4โยฑโ3.4% and varied from 78.6 to 98.2% between pens. Month had no effect on sperm supply or egg fertilization status. Eggs from paired birds (sex ratio 1โ:โ1) had less sperm in the GD than the eggs from pens with a higher sex ratio. In the second year, 150 eggs from seven pens, each containing only one male and either one, two or three females, were studied for 2โweeks at the beginning (winter), middle (spring) and end (summer) of laying. Eggs contained 364โยฑโ45 Sperm~OPVL~/mm^2^ of the GD (range 0โ2880). Season had no effect on sperm supply or egg fertilization. The number of Sperm~OPVL~ varied between pens, assumed to be due to variation between individual males. The number of Sperm~OPVL~ increased as the sex ratio increased only when very highโranking males were excluded from the analysis. Egg fertilization rate was 94.4โยฑโ3.1% but varied from 64.0 to 100% between pens. Egg fertilization was not affected by season or sex ratio. Low fertilization rates were observed in two pens and appeared related to the lack of synchrony between timing of laying and sperm production in the first, and lack of mating in the second pen. We conclude that ostrich flocks generally have high rates of egg fertilization and any infertility is associated with lack of sperm supply.