Simple SummaryDiarrhea is common in weaned piglets. Feed supplementation with Zn is one strategy for preventing such disturbances. A total ban on the use of therapeutic doses of Zn will be introduced from June, 2022 in the European Union; hence, the evaluation of different lower doses and forms of this element is very important and challenging. This paper shows the effects of using different forms of Zn preparations (i.e., zinc sulfate, zinc oxide, and zinc oxide nanoparticles) on weaner rearing results and Zn balance. The obtained results indicate that low levels of zinc oxide nanoparticles can express a similar antidiarrheal action as high therapeutic doses of zinc oxide. In this way, the Zn dose concentration in feed supplements for pigs can be decreased. The application of nanoparticles can lead to measurable benefits, including a higher growth rate and better feed use.The aim of this study was to evaluate the effect of zinc (Zn) supplementation in different commercial forms on the growth performance, health status, and Zn balance of weaners in field conditions. The animals were fed pre-starter (from the 28th to 47th day of life) and starter (from the 48th to 74th day of life) mixtures differing in Zn form and concentration. Group I was given ZnSO4 at 150 mg kg−1; Group II received pre-starter zinc oxide (ZnO) at 3000 mg kg−1 and starter at 150 mg kg−1; and Group III was given 150 mg kg−1 of zinc oxide nanoparticles (nZnO). We found that the average daily gain in Group I was significantly lower, compared to Groups II and III. A commonly accepted level of Zn (150 mg kg−1) as nZnO can be recommended, instead of therapeutic doses of Zn preparations with the same efficiency. Moreover, a lower level of Zn in the diet can prevent the excessive accumulation of this element in waste and, thus, reduce environmental damage.