We assessed the effect of a cholinergic challenge on serial pattern extrapolation in rats. Male and female rats learned a rule-based serial pattern of nosepoke responses in receptacles on the walls of an octagonal operant chamber. The training pattern consisted of 7 chunks of a rule-based serial pattern (123-234-345-456-567-678-781). After learning to a criterion of 90% correct responses on all elements of the pattern, rats were given i.p. injections of 0.6 mg/kg scopolamine hydrobromide 30 minutes before testing on a transfer pattern consisting of the training pattern with an added eighth chunk that was either consistent with pattern structure (chunk “812”) or contained a terminal element that violated pattern structure (chunk “818”). Under scopolamine, and even with impaired performance throughout the pattern, rats in both groups extrapolated known pattern structure, producing approximately 60% rule-consistent responses on the terminal element of both added chunks. Despite scopolamine exposure, both male and female rats extrapolated well-learned pattern structure to a new chunk. In the case of the chunk containing the violation element, when confronted with a new trial requiring a response inconsistent with already learned pattern structure, rats attempted to apply the well-learned rule.