The objectives of this study were to determine the chemical composition, digestibility, in situ N kinetics, and by-pass protein contents of 4 different common vetch varieties grown under irrigation. Four different common vetch varieties (Emir 20/1, Nilufer 17/1, 28/1. and Uludag 31/4) with different characteristics were selected. The vetch plots were planted on June 15 2002 and each variety was randomly assigned to 3 replications. The vetches were harvested by hand using a clipper on September 1. All samples were analyzed for dry matter (DM), ash, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent insoluble nitrogen (ADIN) concentrations. In vitro dry matter digestibility, and in situ degradability of samples at given times were also determined. While the concentrations of DM and ADIN-N did not differ, concentrations of organic matter (OM), CP' NDF, and ADF varied significantly among different vetch varieties (P < 0.05). The water soluble DM content of Nilufer 17/1 was significantly greater then that of 28/1 (P < 0.05), but in situ DM degradabilities after 48-h incubation, in vitro dry matter digestibilities, and metabolizable energy (ME) and net energy for lactation (NEL) values were statistically similar among the vetch varieties (P > 0.05). While the water soluble protein (WSP) concentration was lower, concentrations of potentially degradable protein (PDP), and by-pass CID as a percentage of total digestible CP or DM were significantly greater in 28/1 than in Nilufer 17/1 and Uludag 31/4 (P < 0.05). However, concentrations of non-degradable protein (NDP) and in situ CP degradabilities after 48-h incubation did not differ among the vetch varieties (P > 0.05). It can be concluded that if high by-pass protein content is desired, 28/1 and Emir 20/1 should be preferred over the other varieties. Otherwise, Nilufer 17/1 and Uludag 31/4 should be first choice, based on DM digestibility and CP contents, because the energy contents and percentage of non-digestible CP did not differ among the vetches.