Fully transparent thin-film transistors (TF-Fs) are produced at room temperature by radiofrequency magnetron sputtering. Measuring the drain current (I-DS) as a function of drain voltage (V-DS) at different gate voltages (V-GS) shows the TFTs possess "hard saturation" with on-currents of about 0.2 mA (see Figure) and saturation mobilities of 20 cm(2) V-1 s(-1). The optical and electrical properties and the compatibility of the fabrication process with low-cost plastic substrates show promise for invisible and flexible electronic circuits.