A new technique for tracking of fast fading channels in long code CDMA is proposed exploiting multipath diversity of mobile channels. Based on a linear interpolation model, the proposed method blindly estimates the channel coefficients at the selected positions within a slot up to a scale factor and tracks the time-varying channel using an interpolation. The unknown scale factor can be resolved using only one pilot symbol which increases the bandwidth efficiency. The proposed method can be implemented using several frontends including the conventional matched filter, decorrelator, and regularized decorrelator. A new identifiability condition is established and the performance of the proposed method is assessed through the mean square error and bit error rate.