Pigeons (n= 4) were trained to discriminate cocaine (3.0 nig/kg, i.m.) from saline in a two-key, food-reinforced drug discrimination paradigm. After acquisition of the discrimination, the H1-antihistamines, chlorpheniramine, tripelennamine, diphenhydramine, promethazine and hydroxyzine, were administered before test sessions to determine if these antihistamines shared discriminative stimulus (DS) effects with cocaine. Chlorpheniramine (0.3–5.6 mg/kg) and tripelennamine (0.1–1.7 mg/kg) substituted, (i.e. > 80% cocaine-key responding) in all four birds. Diphenhydramine (0.1–10 mg/kg) and promethazine (0.1–56 mg/kg) substituted for cocaine in three and two birds, respectively, while hydroxyzine (1.0–100 mg/kg) did not substitute for the training drug in any bird. These results, in conjunction with results from a previous study in which several antihistamines shared DS effects withd-amphetamine, suggest that the DS effects of some H1-antihistamines may be similar to those of psychomotor stimulants.