abstract: Growing interest in rapeseed is connected with big possibilities of its use both for industrial and consumption purposes. The quality of rapeseed oil and meal depends on e.g. on the content of antinutritional compounds in the seeds (for example glucosinolates, sinapine, phytic acid). One of the most effective methods for increasing the variability of traits affecting the quality of rapeseed products is mutagenesis. The winter oilseed rape seeds of initial forms (line DH-0120) and M5 generation were collected from 4000 M5 plants after self-pollination. These seeds were analysed for glucosinolate, sinapine and phytic acid content by the use of NIRS method. Because of lower amount of seeds which can be obtained from self-pollinated plants compared to cross-pollinated ones, two NIRS methods were used, i.e. with (additional ring) and without adapter. Mutants showed great increase of variability of analysed traits. For glucosinolates content the values ranged from 3.1 to 80.0 M g-1, sinapine 4.7-11.8 mg g-1 and phytic acid 11.4-16.1 mg g-1. Two methods of analyses of several line DH-120 initial forms showed differences between the results obtained by NIRS with adapter compared to the results obtained by NIRS without adapter (e.g. for glucosinolates the results were 8.0 M g-1 and 11.0 M g-1, respectively). Similar analyses were made with several seed mutant samples and they also showed differences between the data obtained from these two NIRS methods.