To date, 61 patients (29 RA, 26 PsA and six control subjects) have been reviewed. Twenty-one (72%) of the RA patients compared with 11 (42%) of the PsA patients had an increased IMT (normal IMT < 0.5 cm). Mean ± standard deviation IMT values in the RA cohort (0.6 ± 0.14) and in the PsA cohort (0.5 ± 0.15) were significantly greater than controls (P = 0.003, P = 0.03, respectively). IMT values in the RA cohort were greater than in PsA (P = 0.017). There was a significant correlation between IMT and age in the RA cohort. However, mean age in the three groups was not different and no correlation between IMT and age was seen in either the PsA or the control group. The area under the curve (AUC) ESR correlated with the AUC CRP in the group as a whole and in both RA and PsA separately. No correlation was found between the AUC for ESR or CRP and IMT in the different subgroups or in patients with an increased IMT.