Purpose: This study aimed to investigate the effect of concentrated growth factors (CGF) with partially and completely amputated pulp tissue on the histologic outcome of dentin-pulp complex regeneration in immature dogs' teeth with non-infected pulp and apical tissue. Materials and Methods: In this study fifty six immature teeth in four mongrel dogs were involved and simple randomization design was used. The teeth were divided into four groups; group (I): the teeth were left with no treatment (negative control), group (II): the teeth underwent complete pulp extirpation where blood clots filled the root canals (positive control), group (III): the root canals were packed with CGF after complete pulp extirpation and group (IV): the pulp was partially removed leaving the last 1–4mm and the root canals were packed with CGF. The animals were euthanized at 1and 3 months and samples were processed for histological analysis. Results: The best results appeared in CGF treated groups, where the immature roots continued their development in a way simulating the normal and this was represented histologically in closure of the root apex, increasing the root canal wall thickness and
ingrowth of soft tissue into the root canals. However, the pulp architecture and pulpdentin relation appeared better when the pulp was partially removed. Conclusion: Dentin-pulp regeneration of the immature teeth can be promoted by CGF with faster root development and better pulp architecture when the apical 1–4mm of the pulp tissues are left.