AbstractThis letter derives bounds on the bit error rate (BER) of orthogonal frequency division multiple access (OFDMA) systems employing Lth‐order diversity and pulse shaping in Rayleigh fading environments. First, a new probability density function (pdf) of the signal‐to‐interference ratio (SIR) per bit γk in the presence of inter‐carrier interference power PICI and multiple access interference PMAI is derived. The pdf of the sum of square of the multi‐path gain αk is obtained. Second, the BER of OFDMA systems with binary phase shift keying (BPSK) modulation employing maximal ratio combining (MRC) diversity is derived using the SIR pdf. Detailed discussions are given below. Copyright © 2009 John Wiley & Sons, Ltd.