Öz The dislocations formed during the martensitic transformation in Ti-62 % Ta alloys were exânıined by using transmission eleetron mieroseope. Burgers vector of these dislocations which have the same character as the screw dislocations was found as <0001 hep and <110>bcc in the produet and parent phases, respectively. On the other hand, mechanical twins were also învestigated and they were also found to have {0112| <0111 hcp twinning systems in the produet martensite and matrix austenite phases.