Purpose. To determine the effect of the basic organo-mineral fertilizer on the formation and stability of grain quality of winter wheat varieties in multiple crop rotation after black fallow as a predecessor. Methods. Field experiments were based on a multifactorial scheme using split-plot method with due regard to all requirements of the field experiment procedure, analysis of variance was used for statistical processing of the obtained results. Results. Investigation data was given concerning determination of grain quality indices in winter wheat varieties of diffe­rent ecotypes after black fallow as a predecessor depending on organo-mineral fertilizer application in the Left-Bank Forest-Steppe zone of Ukraine. In average for the period of investigation (2011–2015), the highest protein content in winter wheat grains was formed in no treatment variant [in such varieties as ‘Doridna’ (14.1%), ‘Dykanka’ (14.3%) and ‘Levada’ (14.2%)] and in case of organo-mineral fertilizer application [in the varieties ‘Hordovyta’ (14.0%), ‘Kalyta’ (14.0%), ‘Dykanka’ (14.7%) and ‘Levada’ (14.6%)]. The highest content of crude gluten in grains, without regard for the variant of the experiment, was found in the following varieties as ‘Dykanka’ (24.9–25.1%) and ‘Levada’ (23.7–25.4%). Conclusions. It was established that the content of protein and crude gluten in grains as well as the falling number of winter wheat was highly dependent on such factors as the variety and the year of cultivation as compared to the fertilizer background. The following varieties as ‘Hordovyta’, ‘Mulan’, Dykanka’ and ‘Levada’ were very sensitive to the application of organo-mineral fertilizer for the protein content, while ‘Hordovyta’ (2.4%), ‘Levada’ (1.7%), ‘Borvii’ (1.2%) and ‘Mulan’ (1.1%) – for the crude gluten content.