Orthogonal Frequency Division Multiplexing (OFDM) is a widely known modulation scheme used for high speed data transmission (like video) on multipath fading channels. The multipath components of these channels cause a frequency selective fading that seriously degrade the OFDM transmission, due to the erroneous exist on the received data. Time guard-interval is used to reduce intersymbol interference (ISI) and Intercarrier interference (ICI). Convolutional coding protects digital data from errors by selectively introducing redundancies in the transmitted data. In this paper a study of a combined use of Convolutional coding and OFDM technique is presented. The effect of coding rates and constraint lengths of the Convolutional code and the time guard interval of the OFDM symbols are studied under frequency selective environment through computer simulation. Recommendations for design issues are also discussed.