The genus Fumaria belongs to the family Papaveraceae, and those members of the genus which have been investigated have been shown to produce isoquinoline alkaloids. Fumarias have been used medicinally in the past although there seems to be little modern support or evidence for a place in Western medicine, while F. officinalis and possibly other species are used widely in Eastern Europe and deserve more thorough phytochemical investigations. Previous work has shown the genus to be capable of elaborating most of the alkaloid types produced by the Papaveraceae, with the exception of the morphine group. Fumaria muralis ssp. boraei, the commonest species in the Manchester district, had never been examined phytochemically. The plant material was collected in September, authenticated at the Manchester University herbarium where a specimen has been deposited. Fresh leaves (184g) were successively extracted with petrol, chloroform and methanol (stems produced similar alkaloids but in smaller quantities), and each extract was subjected to column chromatography followed by preparative t.l.c. after evaporation. Alkaloids were identified by comparison of u.v., n.m.r. (good quality data obtained on as little as 1mg of sample using Fourier transform spectrometers) and mass spectral data with literature values. The petrol extract produced fumariline, capnoidine (adlumidine) and parfumine; the chloroform extract produced fumarophycine, fumaritine, bicuculline, an unidentified compound resembling eugenol in n.m.r. spectrum but not on t.l.c. or m.s., together with further amounts of fumariline and parfumine; the methanol extract produced three compounds which did not correspond to any known alkaloids, one of which may be the previously unreported N-methylfumaritine. The isolated and identified alkaloids all possess typical Fumaria spirobenzylisoquinoline or phthalideisoquinoline structures. The apparent absence of other structural types (e.g., protopine group, often major alkaloids in Funaria spp.) is curious, and whether this reflects the use of fresh rather than dried material remains to be seen.