The review concerns the recent progress and future trends in the field of biosensors. A brief historic overview is given. Recent achievements in the miniaturization and microfabrication techniques based on lithography and screen printing are described; nanotechnology using surface probe microscopies is shortly discussed. Developments in optical affinity sensing devices are closely linked to the progress in immunochemical biosensors. An increasing use of nucleic acids as biorecognition elements is expected in the near future. Possible market applications and already available commercial devices are also summarized.