Length and width of guard cells and variation in the appearance of stomata pores in the following Arum species: Arum italicum Mill., Arum maculatum var. maculatum L. and Arum maculatum var. immaculatum L. at Zablaće and Normanci location, and Arum alpinum var. pannonicum Terpo., Arum alpinum var. intermedium Schur. in Bilje at the eastern Slavonia and Baranya region were investigated. With regard to guard cells length and width and variation in the appearance of stomata pores, stomata of certain Arum species are considered to be of larger dimensions (≯38 µm). Arum species grown at Zablaće had the longest and widest guard cells as well as the greatest variation in the appearance of stomata pores, followed by those at Normanci, whereas species at Bilje location had the lowest values. The average length and width of the guard cells and variation in the appearance of stomata pores were larger at the lower than at the upper epidermis among each examined Arum species at each location. A significant difference in guard cells length and width and variation in the appearance of stomata pores at both upper and lower epidermis was determined for Zablaće and Normanci location, whereas there was no significant difference in those parameters at Bilje location.