Interleukins play a very important regulatory role in the immunological system. Much attention is payed to understand their complicated activities during parasite infections. To investigate their presence in host organisms techniques of molecular biology have been applied. Nucleotide sequences of many interleukins have been established and analysed. The coding sequences of different species are highly conserved. Rodents are especially investigated because of their usefulness as laboratory models for many animal and human parasitic diseases. Here we take a look at mouse (Mus musculus), rat (Rattus norvegicus), hamster (Mesocricetus auratus) and guinea pig (Cavia porcellus) interleukins and compare their coding sequences and gene structures.