**Abstract**

Basic and translational research on lung biology and pathology can greatly benefit from the development of 3D *in vitro* models with physiological relevance. Lung organoids and lungs-on-chip allow the creation of different kinds of *in vitro* microenvironments, that can be useful for the elucidation of novel pathogenetic pathways, for example concerning tissue fibrosis in chronic diseases. Moreover, they represent important translational models for the identification of novel therapeutic targets, and for preliminary testing of new drugs. In this chapter, we provide a selected overview of recent studies on innovative 3D *in vitro* models that have enhanced our knowledge on chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF), particularly concerning oxidative stress and pro-fibrotic pathogenetic mechanisms. Despite several limitations, these complex models must be considered as complementary in all respects to in vivo studies on animal models and clinical research.

**Keywords:** organoids, organ-on-chip, oxidative stress, lung fibrosis, cell spheroids
