The research was conducted to determine GA4 concentration as growth regulator in acceleration of in vitro elongation for teak shoot explants subculture. The research was done at In Vitro Culture Laboratory, Balai Besar Pengembangan Bioteknologi dan Pemuliaan Tanaman Hutan (BBPBPTH), Sleman, Yogyakarta. The research was arranged in single factor of Completely Randomized Design (CRD) experiment. The treatments consist of 0 mg/l GA4 concentration, 0,1 mg/l GA4 concentration, 0,3 mg/l GA4 concentration and 0,5 mg/l GA4 concentration. Analyzed parameters were percentation of life, percentation of browning, percentation of contamination, number of leaf, number of shoot and shoot height. The ekongation phase of teak in vitro was unsignificantly promoted by GA4 addition in all concentration. The best result in 0 mg/l GA4 concetration was shown in this research by the shoot height (3,35 cm), number of leaf (8,00) and number of shoot (0,9).