An M/G/1 retrial queue with batch arrivals is studied. The queue length K
μ
is decomposed into the sum of two independent random variables. One corresponds to the queue length K
∞ of a standard M/G/1 batch arrival queue, and another is compound‐Poisson distributed. In the case of the distribution of the batch size being light‐tailed, the tail asymptotics of K
μ
are investigated through the relation between K
∞ and its service times.
