Light microscopy is arguably the most important technique to study living systems since it is minimally invasive and, therefore, allows imaging of cells and tissues under physiological conditions. However, the resolution of conventional far-field light microscopy is limited by diffraction such that only structures larger than ∼200 nm can be resolved, which is insufficient for many applications including colocalization analysis. Stimulated emission depletion (STED) microscopy and photoactivation localization microscopy (PALM, FPALM) are recently developed techniques capable of providing an optical resolution down to a few tens of nanometers. We have applied these techniques to study the effect of co-expression of mutant and wild-type desmin on filament assembly.Functioning as an important structural component, the desmin protein forms intermediate filaments found in cardiac, skeletal and smooth muscle cells. Mutations in the gene encoding for desmin were found in arrhythmogenic right ventricular cardiomyopathy (ARVC) patients. As yet it is unknown how desmin mutations contribute to the arrhythomgenic phenotype of ARVC. Some of these mutations cause desmin aggresomes. Therefore, we have investigated how coexpression of mutant and wild-type desmin disturbs filament assembly using dual color super-resolution microscopy. For in vivo dual color labeling, we employed mEosFPthermo, a monomeric variant of the green-to-red photoconvertible protein EosFP, and mIrisGFP, a green-only variant of the photoswitcher/-converter mIrisFP. These studies allowed assessing the impact of different ARVC-related desmin mutations on filament assembly.