Four tryptophan dependent mutants of Claviceps purpurea 1029 N5 were derived by treatment with N-methyl-N'-nitro-N-nitroguanidine (NTG) and protoplasting of the treated fungus. The poor alkaloid production of these mutants required a systematic optimisation of the production media. Malic acid was essential for good alkaloid production. A preliminary attempt to modify the tryptophan moiety of the ergot alkaloid molecule by feeding one selected Trp(-) mutant with tryptophan derivatives (synthons) and preliminary analysis of the extracellular spent medium by HPLC are described. The utilisation of the synthon, 5-methoxytryptophan, from the medium by the Trp- mutant was 99%. The analysis of the spent medium extract of the flask fed with this synthon by HPLC showed the formation of a new peak in the ergot alkaloid region. This peak increased in intensity relative to the time of incubation. Its detailed analysis and further characterisation will be the focus of future studies.