Nowadays, decreasing raw material for the production of pulp from wood has led to search for alternative sources. For this reason, the possibilities of using existing natural species in pulp production are being investigated. White poplar (Populus alba L.), which is a widespread naturally-grown in many parts of Turkey, has the potential to be an alternative pulp raw material. In this study, the fiber dimensions of heartwood and sapwood of white poplar were prepared for microscobic measurements. Also, the relationships between fiber dimensions measured were examined with a specific view to fiber morphology to evaluate their suitability for pulp production. The fiber length of heartwood is higher due to having more 5 year-old groups on it. The changes in the fiber diameter of the sapwood and heartwood by the ages usually showed a polynomial course. The age-related changes were increased from min to average values in the fiber wall width of the heartwood. The felting rate of heartwood indicated that a pulp with proportionally more heartwood would yield a paper with better physical properties, especially tear strength. Based on the results the muhlstep ratio of heartwood and sapwood that both woods are suitable for paper production.