The aim of the research was to determine the influence of preventive application of two different ozone preparations on reproductive efficiency in dairy cows with physiological puerperium. The research was conducted on 404 Holstein cows aged 2–8 years, divided into three groups. The first group consisted of cows treated using 6 intrauterine ozone pearls (RIPROMED OVULI O3®, Novagen, Italy) at once. The second group consisted of cows treated with ozone foam spray (RIGER SPRAY®, Novagen, Italy) application in the body of uterus for 5 s, and the third group was the control group. Cows from the first two groups were observed and treated during early puerperium, 24–48 h after parturition. To assess the reproductive performance of Holstein cows, interval from calving to first insemination (days open to first service, DOFS), interval from calving to pregnancy (days open to pregnancy, DOP), relative pregnancy rate (%), first service conception rate (FSCR, %) and all service conception rate (ASCR, %) were measured. The estimate of hazard ratio (HR) for group B relative to group C for DOFS was 0.62 (p = 0.0002), implying that the relative rate of first service decreased in the control group by 38%. The estimate of HR for group B relative to group C for DOP was 0.65 (p = 0.0006), implying that the relative rate of pregnancy decreased in group C by 35%. Cows treated with Riger spray (group B) became pregnant earlier and had better FSCR and ASCR. It is supposed that the form of ozone preparations and the amount of active substance were decisive. A conclusion may be made that preventive ozone intrauterine application during early puerperal period, especially the foaming form of ozone preparations (spray), improved the reproductive efficacy in dairy cows.