The paper presents the results of developing and creating wireless sensor networks for agriculture and medicine, which the authors have obtained during the past five years. The paper considers wireless sensor networks for estimating the state of plants by the method of chlorophyll fluorescence induction on large areas of agricultural land. The above networks include original smart sensors, built according to flexible architecture and containing elements of artificial intelligence based on neural networks. This construction scheme increases their performance in determining the effect of stress factors of different origins. The authors have constructed a smart remote medical monitoring system based on the wireless sensor network, which employs several wireless data exchange protocols. They also have created a diagnostic system to assess the quality of life and the symptoms associated with the diseases and (or) treatment. It determines the patient’s health state using international and national questionnaires. The operation of proposed smart measuring devices and systems is based on the knowledge-based principles of processing and analyzing the measuring data for making managerial decisions and providing recommendations. Most of the obtained results have been put into mass production.