The mural paintings of the coastal area of Slovenia are of a unique style due to various stylistic tendencies that met there during the Middle Ages. Until now they have been studied only from the art historical point of view. The present research is the first analytical approach to these monuments. The purpose was to find out if (i) these paintings are diverse also in their technique and material, and (ii) if the real a fresco technique is typical of those paintings influenced by Italian tradition, while the lime technique of the central-European influenced murals. To answer these questions, several mural cycles were chosen: Zanigrad (1400-1410), Pomjan (1410-1420), Nozno (1/2 15C), Volarje (2/4 15C), Vremski Britof (1445-1450) and Famlje (1450-1460). All murals were studied in situ and micro-samples of mortars and pigments were analysed in powdered form or as cross-sections using different instrumental techniques: OM, SEM EDS, FTIR and XRD. The composition of mortars is predominantly lime and sand. The pigments applied are mostly of inorganic origin. The painting techniques are different combinations of a fresco, a secco and lime technique. Geographically closer paintings are technically similar. The local tradition was stronger than foreign influences.