Aims: To assess oestrogen receptor (ER)a, ERb, andprogesterone receptor (PR) expression in stage I ovarianadult-type granulosa cell tumours (AGCTs) and correlatethe findings with clinical outcome.Methods: ERa, ERb and PR immunohistochemistry wasperformed on 56 primary, stage I AGCTs. Twelve cases(21%) recurred and hormone receptor staining wascompared in the corresponding primary and metastatictumours.Results: All primary AGCTs expressed ERb and PR, usuallywith strong and diffuse staining, whereas only 20% of tumourswere focally ERa positive. There was no correlation betweenERa or PR expression and outcome. However, primaryAGCTs with low ERb expression had a significantly higherrisk of recurrence. In contrast, all metastatic tumoursexhibited strong ERb staining. No relationship between ERstaining and tumour morphology was identified but there wasmore consistent PR expression in cells at the tumour'stromalinterface.Conclusions: Primary AGCTs typically show an ERanegative and ERb/PR positive immunophenotype. LowERb expression is an adverse prognostic factor in primaryAGCT but metastatic tumours often show up-regulationof ERb. Local microenvironmental factors may influencePR expression. Hormone receptor expression in AGCTmay become increasingly relevant due to developments inselective therapy.