We describe a true three dimensional (3D) microfabrication of photosensitive glass by applying a femtosecond (fs) laser which works at fundamental wavelength. First, designed microstructure was written into the glass sample by a tightly focused fs laser beam (wavelength 775nm, pulse width 145±5fs, repetition rate 1kHz); next, this sample underwent a programmed heat treatment; finally it was immersed into 10% hydrofluoric (HF) acid to take an ultrasonic bath. By this approach, true 3D microstructures with embedded microchannels and microcells are directly formed inside the glass matrix, without extra bonding or adhering procedures in those planar fabrication techniques. Such an approach combines the advantages of high precision in laser microfabrication and cost-effectiveness in chemical processing, therefore, could be a promising tool in futuristic manufacture of micro total analysis systems (μ-TAS) and micro fluidic devices.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.