Abstract: The aim of this study is to evaluate the effects of NaBH4 on pulp and paper properties on conventional kraft pulping. The chemical composition of the Uludag fir wood was determined and this wood was utilized as raw material in pulping experiments. Two sets of pulping experiments were conducted in this study. In the first set, six conventional kraft cookings were made to determine the optimum conventional kraft cooking conditions by altering the cooking time and active alkali taking into account the kappa number and the pulping yield. The obtained results indicated that the optimum kraft cooking condition was accomplished when kraft cook was made using 18% active alkali for a cooking period of 90 min at 170°C. Cooking at these conditions gave 46.3% screened yield, 28.5 kappa number and 1102 cm3 g-1 viscosity for Uludag fir. A second set of cookings was made taking into account the optimum kraft cooking condition and 1, 2 and 3% NaBH4 was added to the cooking digester based on oven dry wood. The results showed a significant decrease in pulping rejects and increase in pulping yield when NaBH4 was added to the cooking digester. This finding indicated higher pulping selectivity of NaBH4 added kraft method. In addition, higher pulp viscosity and brightness were observed in the NaBH4 added kraft method. On the other hand, the strength properties obtained in Kraft-NaBH4 was a slightly reduced compared to the conventional kraft method.