Abstract: A urine-detecting device adapted to be associated with a baby's diaper detects and signals the presence of urine after a sufficient time delay from the initiation of urination so as not to interfere with the baby's act of urination. The signal is audio and optionally with visual. The device is aiming at safety, compactedness and convenience. It combines sensing means and fastening means with signalling means attached to it. A fastening means such as a safety pin with spaced apart electrical conductors on it is used to engage the device to a diaper. When urine bridges the space between the conductive a detection circuit is completed which activates the signal.