Multi-carrier code division multiple access (MC-CDMA) which is a combination of multicarrier modulation and code division multiple access has gained wide acceptance in recent works because of its many advanced features. This paper gives an evaluation of the bit error probability (BEP) of an uplink MC-CDMA system using maximal-ratio combining (MRC) receivers over a Nakagami-m fading channel. An improved and accurate BEP expression for uplink with MRC receivers is derived. Numerical results in term of average BEP show that the proposed expression has excellent accuracy in different conditions, and could serve as an attractive alternative to previously derived expression for evaluating the average BEP of an uplink MC-CDMA system.