Calculations of the primary electroviscous effect have previously been restricted to spherical particles. Here we examine a suspension of randomly orientated rod-shaped particles of length l. Two competing mechanisms are present in a linear velocity field. The flow relative to each rod is largest at the rod ends. When l is large the consequent large distortion of the charge cloud increases the electroviscous effect. On the other hand, the given total charge on a uniformly charged rod is spread more thinly as l increases, and this tends to reduce the electroviscous effect. The balance of these two mechanisms is examined.