To evaluate the management of bronchiolitis in the paediatric intensive care unit (PICU) before and after publication of the national bronchiolitis guidelines in June 2015. All infants treated between 2016–2020 for bronchiolitis in the PICU of Tampere University Hospital at < 12 months of age were included. The data were retrospectively collected from electronic patient records. The current results reflecting the post-guideline era were compared with previously published results for the pre-guideline 2000–2015 period. These two studies used identical protocols. Forty-six infants treated in the PICU were included. During the post-guideline era, inhaled adrenaline was given to 26 (57%), salbutamol to 7 (15%), and hypertonic saline inhalations to 35 (75%) patients. Forty-three patients (94%) received high-flow oxygen therapy (HFOT). Seventeen patients (37%) were treated with nasal continuous positive airway pressure (CPAP) and 4 (9%) with mechanical ventilation.Conclusion: When post-guideline years were compared with pre-guideline years, the use of bronchodilators decreased in agreement, but the use of inhaled saline increased in disagreement with the guidelines. The use of respiratory support increased, evidently because of an introduction of the non-invasive HFOT treatment modality.What is Known:• Oxygen supplementation and respiratory support, when needed, are the cornerstones of bronchiolitis treatment.• Medicines are frequently given to infants with bronchiolitis, especially if intensive care is needed, although evidence of their effectiveness is lacking.What is New:• Nearly all (94%) infants who needed intensive care were treated with HFOT and 37% with nasal CPAP, and finally, only 9% were intubated, which reflects the effectiveness of non-invasive techniques.• When pre- and post-guideline eras were compared, use of racemic adrenaline decreased from 84 to 57%, but use of hypertonic saline increased up to 75%, which disagrees with the current guidelines.