AL-Base, a curated database of human immunoglobulin (Ig) light chain (LC) sequences derived from patients with AL amyloidosis and controls, is described, along with a collection of analytical and graphic tools designed to facilitate their analysis. AL-Base is designed to compile and analyse amyloidogenic Ig LC sequences and to compare their predicted protein sequence and structure to non-amyloidogenic LC sequences. Currently, the database contains over 3000 de-identified LC nucleotide and amino acid sequences, of which 433 encode monoclonal proteins that were reported to form fibrillar deposits in AL patients. Each sequence is categorised according to germline gene usage, clinical status and sample source. Currently, tools are available to search for sequences by various criteria, to analyse the biochemical properties of the predicted amino acids at each position and to display the results in a graphical fashion. The likelihood that each sequence has evolved through somatic hypermutation can be predicted using an automated binomial or multinomial distribution model. AL-Base is available to the scientific community for research purposes.