This research tested the performance of handheld personal laser scanning (PLS) technology for estimating the diameter at breast height (dbh) in a lowland pedunculate oak (Quercus robur L.) forest. More precisely, this study assessed: (i) the accuracy of two, high-end handheld PLS systems (ZEB Horizon and Faro Orbis); and (ii) various scanning schemes with different complexities. Three scanning schemes of different complexity were used by both instruments, and Faro Orbis provided more accurate dbh estimates than ZEB Horizon for each scheme. The results revealed an increase in the PLS data estimation accuracy that corresponds to the increase in complexity of the scanning scheme Additionally, the new ability of Faro Orbis to perform ‘flash’ (static) scans that mimic TLS was also tested, and obtained results revealed that flash scans produce slightly less accurate dbh estimates compared to the most complex walking (mobile) scheme.