Datasets of confocal microscopy images of cardiomyocytes aimed at development of image recognition systems. Images of live and healthy cardiomyocytes with fluorescently stained sarcolemma were assigned into 5 classes according to their development stages. The least developed cardiomyocytes were considered to be at stage 1 (class 1) while the most developed ones were assigned stage 5 (class 5). All other images belong to a class 0.