Distributed Bragg reflection from integrated polymethylmethacrylate waveguides fabricated on corrugated spin-on-glass substrate is reported. Utilizing third-order Bragg resonance, a maximum reflection of 92% from the grating filter is measured at a wavelength of 423.6 nm. A maximum bandwidth of the Bragg reflection is found to be ∼0.5 nm for a 6 mm long filter. The broad bandwidth and the significant transmission loss (∼90%) away from resonance are believed to be related to the radiation coupling by the grating. It is shown that the radiation loss can be minimized without sacrificing high reflectivity by limiting the waveguide length to 0.5 mm, the saturation length of the Bragg reflector.