Two new human ABC transporters, ABCC11 and ABCC12, were cloned from a cDNA library of human adult liver. ABCC11 and ABCC12 genes consist of 30 and 29 exons, respectively, and they are tandemly located in a tail-to-head orientation on human chromosome 16q12.1. The predicted amino acid sequences of both gene products show a high similarity with ABCC5. The transcripts of ABCC11 and AECC12 genes were detected by PCR in various adult human tissues, including liver, lung, and kidney, and also in several fetal tissues. By searching cDNA libraries from various human tissues, we have identified alternative splicing variants of ABCC11 and ABCC12 genes at significantly high frequencies. One splice variant lacking the exon 28 corresponded to about 25% of total ABCC11 gene transcripts. Furthermore, four splicing variants encoding putatively short peptides were predominant in ABCC12 gene transcripts. Those splicing variants may represent diverse biological functions of these ABC transporter genes.