The long-term recording of humidity and temperature conditions is very important in the phar- maceutical industry, production processes, storage, test facilities and many other areas. Once logged, the temperature and humidity data can be evaluated statistically. This provides valuable information on conditions that can have an influence on people and product quality. Wireless transmission saves wiring costs and simplifies data transfer from inaccessible points. ROTRONIC data loggers fulfill the requirements of 21 CFR Part 11 and GAMP5 completely. The data can be read out easily with the HW4 software. The measurements can be recorded either in tamper-proof LOG mode or in easily accessible Excel files.