Although language endangerment is often associated with languages which have few speakers, it has now become an emerging fact (e.g. Brenzinger and De Graf (2006)) that languages with huge populations can also be vulnerable to endangerment. In Nigeria for instance, both the major and non-major languages, as noted by Emenanjo (2007), are not safe when examined in the light of the evaluative factors on the UNESCO (2003) language vitality index. Thus, as Nigerians increasingly abandon the use of their indigenous languages in all domains of life, including the home, the present paper examines the phenomenon of vocabulary endangerment in two ‘unequal’ Nigerian languages, Igbo and Ibibio in order to assess how faithful speakers of both languages are, in using some indigenous vocabularies of their languages in their daily interactions. Respondents who were grouped into clusters were chosen from Aba and Uyo metropolises where Igbo and Ibibio are indigenously spoken respectively, and were presented with a list of 260 Igbo/ Ibibio nouns categorized into 24 groups and their equivalents in English. They were further asked to indicate ‘yes’ or ‘no’ to whether they would use each indigenous Igbo/Ibibio noun or its English equivalent any time such a word comes up in their day-to-day interactions done in Igbo/Ibibio language. The findings of the paper among others reveal that there is evidence of vocabulary endangerment in the speech of both the Igbo and Ibibio respondents. However, compared with Igbo respondents with a total average of 48.6% usage of the vocabulary items studied, Ibibio respondents had a total average usage of 68.1%. This shows that the Igbo respondents in Aba unlike the Ibibio ones in Uyo manifested a much higher apathy in the use of their vocabulary items, a fact which obviously shows that vocabulary items are more endangered in the speech of Igbo respondents. However, given the fact that Igbo has a much higher population of speakers with also a much bigger geographical area covered by its speakers, there is the need for this kind of study to be extended to other metropolises in the other states (Anambra, Enugu, Ebonyi and Imo) of the South-East of Nigeria where Igbo is homogenously spoken. Such a survey when compared with the result of Ibibio as presented here would give a much clearer picture of the level of endangerment between Igbo and Ibibio.