As an alternative to five daily fractions per week, one large fraction per week has been used to treat patients with stage III carcinoma of the cervix. This regime was greatly appreciated by our village women who could attend for weekly treatment from their homes. The weekly dose was matched with our previously acceptable daily fractionation using NSD, TDF and CRE values. In 24 patients the early reactions and tumour response were acceptable. Late rectal complications commencing seven months after treatment have, however, developed in all surviving patients with the new regime. The complications have been far more severe than those of a matched group of 24 patients treated with daily fractions and the schedule using one fraction per week has been abandoned. "Iso-effective" doses for the two techniques were selected from the NSD, TDF and CRE tables. This study clearly indicates that for one fraction per week the doses predicted are not "iso-effective" as far as the normal tissues of the pelvis are concerned.