We assessed the inter-relationships between the Short Form 36 (SF-36) physical and mental function in 220 patients with onset cases of mild and moderate depression and 913 adults with early and established rheumatoid arthritis (RA) through secondary analysis and compared both scores with the UK general population norms. In depression and RA the SF-36 total scores showed significant impairment across the spectrum of both domains compared with age-specific UK normative score. In RA mental health and role, mental scores were highly correlated with other SF-36 domains. In depression there was little evidence of such inter-relationships. Mental health and role mental domains were lowest in active RA (disease activity scores (DAS28) over 5.1). They had strong correlations with the vitality and social function SF-36 sub-scores and weak correlations with the physical function and role emotional sub-scores. Patients with long-term conditions require comprehensive care. At present it is unclear how best to combine treatment of RA synovitis with the management of mental health problems. Mental health symptoms are present from the earliest stages of RA and it may be appropriate to initiate multidisciplinary care as soon as practicable, although its efficacy requires a further detailed study across primary and secondary care.