Nitrogen use efficiency (NUE) has become the second priority after improving the drought resistance for many crops. Screening of potato breeding clones under in vitro conditions for NUE, N uptake efficiency (NUptE) and N utilization efficiency (NUtE) (N efficiencies) might be promising. However, it is not yet clear whether genotypes have similar pattern of N efficiencies both under in vitro and field conditions. In the study carried out in Priekuli, Latvia, 6 genotypes having early maturity type and 7 medium late to late maturity type genotypes (MLLG) were tested both under in vitro and field conditions. In vitro tests were performed in three series and had 4 replications in each series. N rates in medium were 60 (standard); 20 and 7.5 mmol L-1. Field trial was carried out in 2020, four N kg ha- 1 fertilizer doses were applied (N0, N60, N120, N180), 4 replications were used. In general, at lower N doses, potatoes have a higher N efficiencies, that are also higher for late varieties. These findings were also confirmed in field trials of this study. NUE was significantly higher for MLL genotypes at all N doses, except N0. Higher N efficiencies at lower N rates were confirmed also under in vitro conditions, but no significant correlations between the N efficiencies in vitro and in field trials were found. Moreover, the pattern of efficiency depending on maturity type differed from that obtained in field trial. Early genotypes had significantly higher NUE than MLLG at two lower N rates. This finding suggests that the maximum amount of N available in the medium limits use of in vitro testing method, as the potential of MLLG cannot bet fully realized. This research is supported by the Latvian Council of Science in the framework of FLPP project lzp-2019/1-0371