There is a consensus that open-access breast imaging for general practitioners is inappropriate since the process omits an expert clinical examination and fine needle aspiration cytology. However, it was decided to test this hypothesis by comparing the outcome of breast referrals in a district with both an open-access imaging and a one-stop clinic. The time from referral to definitive diagnosis in all women with breast cancer was compared over a 12 month period in 1996. Of 1049 women referred for open-access imaging 20 (2%) were found to have breast cancer compared with 91 (9%) of 995 women referred to the one-stop breast clinic. There was a longer interval before the diagnosis of breast cancer was made in cases referred for open-access imaging compared with cases referred to the one-stop breast clinic (mean 63 vs 35 days). However, if patients with advanced disease are excluded the mean interval was 63 vs 44 days. The mean tumour size of breast cancers in cases referred to open-access imaging was smaller (1.5 vs 2.3 cm), there were fewer grade 3 tumours (10% vs 39%), and there was a lower rate of axillary lymph node metastases (20% vs 32%) compared with cases referred to the one-stop breast clinic. The longer interval for the open-access patients was largely due to administrative delay and the 3 patients with a delay of more than 3 months had all had a triple assessment which was false negative. This study does not support the hypothesis that open-access mammography is unsafe and should be withdrawn.