Pedagogical Content Knowledge (PCK) refers to certain knowledge of teacher in a particular topic, considered as an act of teaching to deal with students in a particular way. Since PCK allows a science teacher to provide quality teaching, this qualitative multiple case study aims to explore the nature of science teachers' PCK on the topic "Genetics" of grade eight in Bangladesh by contributing to the existing literatures on PCK. Total four teachers, one from each school, participated in this study through filling in Loughran's (2006) developed CoRe (Content Representation) template which can provide an overview of how teachers conceptualize the content of particular subject matter. Classroom observation and semi-structured interviews with those teachers were also conducted. By ensuring the trustworthiness of the research, this study presented a thematic and cross-case analysis based on the components of PCK. The results showed that, three out of four teachers belong from novice level of PCK which implies that they could not achieve the maximum PCK components even if they worked for years, yet one teacher failed to meet the criteria of novice level even. Apart from that, the participants could not meet the requirements of teaching for scientific literacy in full extent. Since this study claims to shed a light on the present condition of science teachers' PCK and their daily challenges, it would facilitate the policy makers and educationists alike in developing curriculum and textbook on "genetics" section and conducting teachers' training.