The use of non-feather pillows has increased over the last few decades. Recently, we found significantly higher levels of dust mite allergens in synthetic pillows than in feather ones. This study investigated the levels of pet allergens in feather and synthetic pillows. Dust samples were collected from 14 pairs of pillows (consisting of one synthetic fibre-filled and one feather-filled). Each pair of pillows had been on the same bed for at least 2 years. The pillows were vacuumed for 1 min on each side through a 355-μm diameter mesh onto a 5-μm vinyl filter, producing a sample of fine dust. Samples were extracted, and cat (Fel d 1) and dog (Can f 1) allergens determined using monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA). Results were expressed both as total amount of allergen recovered and concentration of allergen per unit weight (ng/g). Total levels of pet allergens were significantly higher in the synthetic pillows (Fel d 1:6.7-fold difference [95% CI 1.5-29.7], p = 0.01; Can f 1: 8-fold difference [95% CI 1.6-39.5], p = 0.01). Similarly, when the results were expressed as ng/g, synthetic pillows contained significantly more allergens than feather pillows (Fel d i: 3.7fold difference [95% CI 1.3-10.1], p = 0.01); Can f 1: 4.4-fold difference [95% CI 1.5-13.2], p = 0.01). We have therefore demonstrated that synthetic pillows contain significantly more pet allergens than feather pillows, supporting the view that tightly woven encasements surrounding feather pillows act as a barrier for allergens.