Performance degradation of uplink OFDMA and uplink MC-CDMA under Wiener phase jitter is pointed out in this paper using theoretical and simulation results. Beginning by characterizing the Wiener process, signal to noise degradation of presented waveforms is derived. Under the assumption of full load and small jitter, the degradation is shown to be varying with jitter variance and time. The main conclusion that can be achieved is the strong degradation that may occur to frequency locked multicarrier systems in the presence of Wiener phase jitter.