Stability of protective forests above the main road Godovič - Idrija was analysed on two research plots. One plot was observed in a managed stand whilethe other in an unmanaged stand. On each plot stand parameters, coarse woody debris, stumps and natural regeneration of tree species were analysed. Trees were registered on two whole plot areas each measuring 3500 m2 while regeneration was observed on 70 subplots (1,5 x 1,5 m). Natural regeneration of tree species was registered also on a larger open surface, on 10 subplots. Ecological stability in protection forests is assured by sufficient natural regeneration, diverse composition of species and optimal forest structure. Regeneration was insufficient on the unmanaged plot. Outgrowing to higher treediameters was not ensured. Regeneration was successful on the managed plot. On the large cleared area a dense ground vegetation obstructed the development of seedlings. On all plots the protective function was not ensuredsince the distance between the trees should not exceed 40 m. Because this distance was exceeded the falling stones could gain high speed and destructive power. Rockfall hazard for a rock of one meter diameter, calculated using Rockfor.net tool, was high on both surfaces (17-20 %). The suggested solution is to reduce the breast diameter and increase the density of trees. The density is sufficient in case that in calculation are consideredalso dead stationary trees and stumps, both higher than breast height. Fallen trees can be positioned transversely to slope thus serving as an obstacle for falling stones.