We studied wood formation in beech (Fagus sylvatica), using intact tissue samples containing xylem, cambial zone and phloem. The samples were taken from adult trees growing at the forest site Panška reka near Ljubljana at weekly intervals during the 2006 vegetation period. Light microscopy (LM), UVmicrospectrophotometry (UMSP) and transmission electron microscopy (TEM) were used for analyses. LM (bright field and polarization mode) and image
analysis were used for investigation of cell divisions in the cambial zone and xylem formation. We determined lignin content in forming cell walls with UMSP. TEM was used to follow the deposition of cell wall layers. The methods used enabled us to investigate wood formation at different levels. Cell divisions started at the end of April and ended from the end of July till mid August. The main part of the growth ring in the wood was formed from May till July. The first formed vessels were completely formed in approximately one month and the first formed fibres in approximately two months.