Research was aimed at knowing the effect of increasing ammonium concentrations on meloidogyne javanica development in tomato roots growing in axenic culture. Egg massaes of M javanica were exposed to deficient ammonium concentration (1.5 PPM NH4). Stages of nematode development inside roots were then observed at weekly interval for three weeks. Result of the research showed that increasing ammonium concentration after root infection suppressed nematode development. In roots transferred to high ammonium concentrations, fewer nematodes matured and most of those that did were males. In addition, there were also fewer galls and lower root dry weights in increased ammonium than those with constant low ammonium concentration.