Underplanting is an effective silviculture tool, for increasing structural and species diversity. Differentiated forests have higher adaptation potential, together with stable providing of ecosystem services. The objective of this work was to evaluate biometric parameters and development of silver fir (Abies alba Mill.) individuals underplanted in scots pine (Pinus sylvestris L.) stand in first years after establishing and during the next growth periods. We established 9 permanent plots in Nízke Beskydy mountains in north-east Slovakia. We focused on four forest stands, with age of underplanted individuals from 11 to 60 years. The selected succesional pine stands were in the altitude from 440 to 540 m. Analyses in 11 year old underplanting were focused on basic biometric parameters and damage of 272 individuals, morphology and incremental parameters of 27 individuals. Subsequently, the impacts of shading stand and lateral competition were characterized. Then we evaluated the structure and productivity potential in older stands. The results were, that crown layer of pine stand is sufficiently permeable for light, and until 80% of shading degree the fir samplings doesn̕ t create shady shaped crown. The increment parameters of underplanted individuals are in the significant negative correlation with parameters of shading stand. With the increase of the shading degree, basal area and volume of pine stand, the height increment (relative growth ratio) was decreasing from 26% in open field conditions to 19.4%-8.5% under pine canopy. In general, individuals in open field reached the height 1.3 m 2 times faster, than individuals under canopy (in average 6 years). Lateral competition between individuals has a stronger significant impact in open field conditions than under canopy layer. The differences between dominant and repressed individuals grows proportionally with lateral competition increase. Underplanted pine stands have potential to reach a high quality production in a continuous multistorey structure. The risk of uneven aged fir forest formation after pine canopy extraction should be prevented with the admixture of beech and other suitable species to underplanting. Actually, because of the high game abundance, we can̕ t utilize the growth potential of silver fir without protection measures.