Black locust is one of the most commonly planted exotic tree species in the world. It has a crucial role in mitigating the negative effects of climate change. Its increment analyses have a key role in forest planning. Increment is added to the wood stock of the forest over and over again, and only this continuous replenishment makes the sustainable forest management possible. This study presents the results of the analysis of periodic annual increment (PAI) by diameter (dbh) and volume (v) of two differently aged black locust (Robinia pseudoacacia L.) stands, growing under similar ecological conditions. The main correlations are as follows: PAI<sub>dbh</sub> and diameter at breast height: r = 0.601 and 0.704 (P = 0.01); PAI<sub>v</sub> and mean tree volume (v): r = 0.721 and 0.849 (P = 0.01). The presented correlations clearly demonstrate the importance of individual differentiation within a stand.