Two species of chthamalid barnacles are well established from the upper to the lower limit of the midlittoral zone on the rocky shores of the North Adriatic Sea: Chthamalus stellatus, Poli and Chthamalus montagui, Southward. The present study deals with the vertical distribution and abundance for each species at two localities of the Istrian peninsula coast (North Adriatic Sea). For this purpose chthamalid populations were monitored in 2015 along the Slovenian marine coast (Bay of Koper, Gulf of Trieste) and along the Croatian marine coast, near Rovinj (west Istrian coast), both on limestone. The main aim of the study was to establish if there was a relationship between the vertical distribution and abundance of these two species at different spatial scales: small (between sites, about 1 kilometer) and large (between localities, 10s of kilometers). The selected localities are slightly different in tidal range, in orientation and wave exposure. Three sites were randomly selected at each locality and two transects per tidal level (upper, middle and lower) were chosen on each site. The abundance of each chthamalids species in 1 dm2 plots was determined at three different tidal levels along each transect. The results indicated that the vertical distribution of C. montagui and C. stellatus was very similar between localities and even among sites, but their abundance varied. At both localities, C. montagui was more abundant in the upper and middle tidal levels, while C. stellatus was more abundant at the lower tidal level. It was also found that C. montagui was more abundant in sheltered conditions (Bay of Koper), while C. stellatus on the coast more exposed to the wave action (near Rovinj), at all tidal levels. Dvije vrste ciripednih rakova vitičara dobro su razvijene od više do niže gornje granice mediolitoralne zone na stjenovitim obalama sjevernog Jadrana: rak vitičar brumbuljak (Chthamalus stellatus, Poli i Chthamalus montagui, Southward). Ova studija se bavi vertikalnom raspodjelom i brojnošću ovih vrsta na dva lokaliteta na obalama istarskog poluotoka (sjever Jadranskog mora). U tu svrhu su 2015. promatrane populacije ciripeda duž slovenske obale (Koparski zaljev, Tršćanski zaljev) te duž hrvatske obale u blizini Rovinja (zapadna obala Istre), obje na vapnencu. Glavni cilj istraživanja bio je utvrditi postoji li povezanost između vertikalne raspodjele i brojnosti ovih dvaju vrsta u različitim prostornim skalama: mala (među lokalitetima, otprilike jedan kilometar) i velika (među lokalitetima, deseci kilometara). Odabrani lokaliteti pomalo se razlikuju po rasponu plime i oseke, smještaju i izloženosti valovima. Nasumce su odabrana tri mjesta na svakome od ovih lokaliteta i dva presjeka za razinu plime i oseke (viši, srednji i niži) odabrana su na svakoj pojedinoj lokaciji. Brojnost pojedine vrste chthamalida u dijelovima od 1 dm2 određeni su trima različitim razinama duž svakog presjeka. Rezultati su upućivali da je vertikalna raspodjela C. montagui i C. stellatus vrlo slična na svim lokacijama pa čak i na svim kontrolnim mjestima dok je njihova brojnost varirala. Na obje lokacije, C. montagui je bila brojnija pri nižim razinama plime i oseke. Također smo utvrdili da je C. montagui brojnija u zaštićenijim uvjetima (Koparski zaljev), dok je C. stellatus brojniji na obalama koje su izloženije valovima (blizu Rovinja), prilikom svih razina plime i oseke.