L-Dopa decarboxylase (DDC) has been cloned from several species and was shown to undergo alternative splicing within its 5′-untranslated and coding regions. In this report we describe a novel splice variant of DDC mRNA in human tissue, lacking exons 10 - 15 of the full-length transcript but including an alternative exon 10. The isolated alternative human DDC cDNA (alt-DDC) was cloned from human placenta, and was found to be of the neuronal type. Northern blot analysis indicated that the alt-DDC transcript is expressed in high levels in human kidney. Our results demonstrate the detection of a new alternative splicing event within the coding region of the human DDC mRNA, further suggesting that the single copy human DDC gene undergoes complex processing leading to the formation of multiple mRNA isoforms.