Using polyclonal antibodies raised against human pancreatic procarboxypeptidases, a full-length cDNA coding for an A-type proenzyme was isolated from a lambda gt11 human pancreatic library. This cDNA contains standard 3' and 5' flanking regions, a poly(A)+ tail and a central region of 1260 nucleotides coding for a protein of 419 amino acids. On the basis of sequence comparisons, the human protein was classified as a procarboxypeptidase A1 which is very similar to the previously described A1 forms from rat and bovine pancreatic glands. The presence of the amino acid sequences assumed to be of importance for the zymogen inhibition by its activation segment, primarily on the basis of the recently reported crystal structure of the B form, further supports the proposed classification.