MUC5B rs35705950 (G/T) is strongly associated with idiopathic pulmonary fibrosis (IPF) and also contributes to the risk of interstitial lung disease (ILD) in rheumatoid arthritis (RA-ILD) and chronic hypersensitivity pneumonitis (CHP). Due to this, we evaluated the implication of MUC5B rs35705950 in antisynthetase syndrome (ASSD), a pathology characterised by a high ILD incidence. 160 patients with ASSD (142 with ILD associated with ASSD [ASSD-ILD+]), 232 with ILD unrelated to ASSD (comprising 161 IPF, 27 RA-ILD and 44 CHP) and 534 healthy controls were genotyped. MUC5B rs35705950 frequency did not significantly differ between ASSD-ILD+ patients and healthy controls nor when ASSD patients were stratified according to the presence/absence of anti Jo-1 antibodies or ILD. No significant differences in MUC5B rs35705950 were also observed in ASSD-ILD+ patients with a usual interstitial pneumonia (UIP) pattern when compared to those with a non-UIP pattern. However, a statistically significant decrease of MUC5B rs35705950 GT, TT and T frequencies in ASSD-ILD+ patients compared to patients with ILD unrelated to ASSD was observed. In summary, our study does not support a role of MUC5B rs35705950 in ASSD. It also indicates that there are genetic differences between ILD associated with and that unrelated to ASSD.