In the process of chondrogenesis, chondroprogenitor stem cells differentiate to chondroblasts and then to chondrocytes. During this procedure, the differentiating cells produce cartilage-specific extracellular matrix (ECM) proteins. However, the signaling pathways that regulate chondrogenesis, and the compounds influencing these pathways, have not been fully mapped. There has been a study where losartan, an angiotensin receptor blocker antihypertensive drug, was applied in a rabbit model with osteochondral defects, and improved articular cartilage repair mechanisms have been observed. Following up on that study, we were curious as to what the molecular background of those published results could be. We aimed to check whether losartan had any observable effects on in vitro chondrogenic differentiation in a chondrogenic model. We established high-density micromass cell cultures derived from distal parts of limb buds of early-stage chicken embryos. We treated the chondrifying cell cultures every second day with 10-6 mol/L, 10-8 mol/L, and 10-10 mol/L concentrations of losartan. The cell cultures were collected on different culturing days (1, 3, 6, 10, 15). We performed MTT assay to compare mitochondrial activity of cells following losartan treatment. We stained the cultures with dimethylmethylene blue (DMMB) to check metachromatic ECM production. Gene expression levels of chondrogenic and osteogenic marker genes (SOX9, COL2A1, ACAN, RUNX2) were monitored using RT-qPCR. The MTT assay showed significantly lower (p<0.05) mitochondrial activity in cultures that received higher concentrations (10-6 mol/L, 10-8 mol/L) of losartan on days 3, 6 and 10. Interestingly, by day 15, losartan increased mitochondrial activity. Losartan enhanced chondrogenic differentiation by culturing days 10 and 15, as revealed by DMMB staining analysis. When we looked at gene expression levels, we observed varied results. On day 3, chondrogenic marker genes were upregulated by losartan treatment, but on day 10, the osteogenic transcription factor RUNX2 was also showing significantly higher expression levels. These results suggest that losartan had a chondro-stimulatory effect in micromass cultures. Our data has interesting implications for patients with degenerative joint disorders such as osteoarthritis.