Standardized ileal digestibility (SID) of amino acids (AAs) by growing pigs was determined in blood meal and six sources of meat and bone meal (MBM). Eighteen ileal-cannulated barrows (initial body weight: 69.3 ± 4.4 kg) were randomly allotted to a replicated 4 × 9 incomplete Latin square design with four periods and nine diets, giving eight replications per diet. One diet included 33% soybean meal (SBM) as the sole source of AA. Seven diets contained 9% blood meal or 9% of one of the six sources of MBM and 22% SBM as the only AA containing ingredients. The last diet was a nitrogen (N) free diet. Results indicated that the SID of all AAs were different (P < 0.05) among the six sources of MBM, but the SID of lysine (Lys) could not be predicted from the ratio between Lys and crude protein. For some, but not all AAs, the average SID in MBM was greater (P < 0.05) than in blood meal, but for most AAs the SID in MBM was less (P < 0.05) than in SBM. It is concluded that, as is the case for most other co-products, differences in concentration and SID of AAs among sources of MBM exist.