This study further explores the association between schizophrenia and caffeine use by combining two prior published Spanish samples with two Spanish long-term inpatient samples from the same hospital. The specific aims were to establish whether or not, after controlling for confounders including tobacco smoking, the association between schizophrenia and caffeine is consistent across schizophrenia samples and across different definitions of caffeine use. The frequency of caffeine use in schizophrenia inpatients was not significantly higher than that in non-schizophrenia inpatients