This study aims to determine the effectiveness of antibacterial pineapple peel extract (Ananas comosus. L) on Ralstonia solanacearum growth. Pineapple peel extract (Ananas comosus.L) contains antibacterial compounds of bromelin and tannin enzymes that are able to inhibit the growth of plantcausing bacteria, Ralstonia solanacearum. Ralstonia solanacearum bacteria will be given 5 treatments with pineapple peel extract 10%, 30%, 60%, 100% and positive control Streptomicin sulfate 0.01%, each repeated 5 times. The test was performed by adding 100μl of Ralstonia solanacearum suspension which was diluted into 15ml Tetrazolium chloride agar medium which was given 100 ml of pineapple peel extract. The results showed that the treatment of pineapple peel extract had a significant effect on the growth of Ralstonia solanacearum. The average number of treated bacteria 60% (4x107 CFU), 100% (8x106 CFU) and Streptomicin sulfate 0.01% (4x106 CFU) was significant (P <0.01) higher than the number of bacteria treated by concentration 10% (1.79x108) and 30% (1.27x108). Consentration 100% pineapple peel extract (Ananas comosus.L) is the most effective in inhibiting the growth of Ralstonia solanacearum. Thus it can be concluded that pineapple peel extract (Ananas comosus.L) is effective as an antibacterial Ralstonia solanacearum.