The identification of factors that might affect the relationship between patients' and carers' psychological distress has received insufficient attention to date. A meta-analysis was conducted with 21 independent samples of cancer patients and their carers, to quantify the relationship and difference between respective measures of psychological distress. Correlation coefficients and standard differences were extracted from 21 studies that met pre-defined inclusion criteria. Random effects models were used. Variables that modified this relationship were examined with potential causes of heterogeneity explored. Analysis confirmed the positive association between patient and carer psychological distress (r = 0.35, P<0.0001), and indicated that patients and carers did not experience significantly more or less psychological distress than one another (P = 0.64). Subgroup analysis was performed to explore potential sources of heterogeneity, and initial findings indicated a relationship between time since diagnosis and the strength of correlation between patient and carer psychological distress. The meta-analysis was limited by the large clinical and methodological variability between studies, and further systematic prospective research is required. This preliminary evidence suggests that early intervention with the patient and their carer could prevent later development of psychological distress in both members.