In this paper, we study the effect of radio frequency (RF) impairments and channel estimation error (CEE) in multiuser two-way and one-way amplify-and-forward relay network. In particular, for both the networks, we derive the approximate signal-to-noise-plus-distortion-and-error ratio expressions and then use them to evaluate the overall outage probability and their asymptotic analysis. Based on the analytical results, it is shown that the RF impairments and CEE can severely degrade the outage performance, and even reduce the diversity order to zero. Unexpectedly, in two-way relay system, we notice that the system performance decreases with increasing number of users in a multiuser environment. Finally, numerical illustrations are done to validate our analytical expressions with the help of Monte-Carlo simulations. Index Terms-Two-way relaying, one-way relaying, multiuser , AF relaying, channel estimation error, radio frequency impairments, overall outage probability, asymptotic analysis.