Spiders (Araneae) are among the largest and most diverse order of arachnids in Slovakia. In our country we recorded 969 species (Gajdoš et al. 2018). They can be distinguished from other arachnids by several characters. Spiders (especially species from the family Pholcidae) are commonly mistaken for harvestmen. In the comparison spiders have cephalothorax and abdomen joined by a pedicel. They have mostly eight or six eyes, excluding some true cave-dwellers which can have only rudimentary eyes. Chelicerae are two-segmented and on the distal segment (the fang) is the opening to the venom canal (some spiders, e.g. family Uloboridae, lack poison gland). On the abdomen they have got spinnerets that permits spiders to produce many kinds of silk for special purposes as webs, retreats and cocoons. Size of Slovakian spiders range from one millimeter dwarfs up to several centimeters beautiful giants (the biggest is Lycosa singoriensis). Spiders can be found in all kinds habitats. Monitoring of the synanthropic localities showed increasing of imported species. Our species are not toxicologically significant and only few species can be aggressive while they are disturbed or by inappropriate manipulation (e.g. Cheiracanthium and Lycosa).