This study examined the perceptions of pre-service biology teachers about their competencies in biology applications. The study was conducted on pre-service biology teachers who have taken all application courses since the first year of the university. One hundred and fifty pre-service biology teachers participated in the study. The data were collected between the years of 2003-2007 period, each year with a different group consisting of 30 pre-service biology teachers. The pre-service teachers were asked how competent they perceived themselves in effectively using the instruments in the biology laboratory, in teaching the subjects covering laboratory techniques and methods, ensuring maintenance of the instruments in the biology laboratory and establishment of a biology laboratory in a secondary education institution. The responses were on a 5-point Likert type scale, ranging from 5 (quite competent) to 1 (quite incompetent). In addition, by means of two open-ended questions, the students were asked if they considered themselves inadequate, and if they felt themselves inadequate, whether or not they had suggestions to overcome their inadequacy. The responses were analyzed by using content analysis procedures. The study results showed that pre-service teachers found themselves “partially competent” in “using effectively the instruments in the biology laboratory” and “teaching the subjects covering laboratory techniques and methods” ( =3.33; =3.29, respectively). Moreover; a significant, positive relationship was found between pre-service teachers’ scores on “using effectively the instruments in the biology laboratory” and “teaching the subjects covering laboratory techniques and methods” (r=0.73, p=0.01).