This study aimed to analyze how the ability of biology teachers forum (called as MGMP Biology teachers) on the 21st century TPCK. This case study was conducted on 10 MGMP Biology teachers from different schools as the participants. The data were collected by using a questionnaire. The data analysis was conducted descriptively based on 7 components in TPCK of the 21st century: Pedagogical Knowledge (PK), Content Knowledge (CK), Technological Knowledge (TK), Pedagogical Content Knowledge (PCK), Technological Pedagogical Knowledge (TPK), Technological Content Knowledge (TCK) and Technological Pedagogical Content Knowledge (TPCK). The results showed that the mean PK (2.90), CK (2.40), TK (2.25), PCK (1.92), TPK (1.93) and TPACK (1.97) TCK with averages (1.73) was categorized as very less ability. This result shows that the ability of 21st century TPCK of the teachers still needs to be improved on the aspects of content mastery, pedagogy and technology.