Abstract: This research aimed to design a control system for greenhouse over internet so that its monitoring and control can be remotely done.The designed system consists of hardware（sensors，microcontroller，switches，computer，webcam，actuators）and software（acquisition and control）.System′s performance was tested by installing it in a model greenhouse equipped with actuators（fans，pump，sprayer，mechanical shading，and camera rotator）and connecting it to a computer network.Hydroponic lettuce（Lactuca sativa）cultivation was monitored during its entire growing period while microclimatic parameters including temperature，humidity，light，and moisture content were controlled under three operating modes（manual，automatic，and timer）.Fan，pump，and sprayer were controlled using switches to ensure that the microclimatic parameters are maintained within desired range.Mechanical shading and camera rotator were controlled proportionally using servo motor，driven by PWM signals.Performance of the system under three operating modes was evaluated and compared.The results indicate that controlling four parameters including temperature，humidity，light，and moisture content can be successfully done remotely via internet using Remote Desktop.Surveillance unit provides pictures of plant growth that offers additional information to be considered for making a control decision.