Although eukaryotic mitochondrial (mt) ribosomes evolved from a putative prokaryotic ancestor their compositions vary considerably among organisms. We determined the protein composition of tandem affinity purified Trypanosoma brucei mt ribosomes by mass spectrometry and identified 133 proteins of which 77 were associated with the large subunit and 56 with the small subunit. Comparisons to bacterial and mammalian mt ribosomal proteins identified T. brucei mt homologs of L2 - L4, L7/12, L9, L11, L13 -17, L20 - 24, L27 - 30, L33, L38, L43, L46, L47, L49, L52 and S5, S6, S8, S9, S11, S15 - 18, S29, S34; although the degree of conservation varied widely. Sequence characteristics of some of the component proteins indicated apparent functions in rRNA modification and processing, protein assembly and mitochondrial metabolism implying possible additional roles for these proteins. Nevertheless, most of the identified proteins have no homology outside Kinetoplastida implying very low conservation and/or a divergent function in kinetoplastid mitochondria.