To determine the effects of mixing charcoal with pyroligneous acid (pyroligneous acid 1 : charcoal 4 ; Sannekka E) on sucrose synthesis in netted melon fruit, five experiments were carried out at 3 locations from 1990 to 1995. All the experiments indicated higher sucrose content in the fruit supplemented with Sannekka E than without Sannekka E. The activity of sucrose phosphate synthase (SPS) increased as the fruit matured, irrespective of Sannekka E application, but the increase was higher in the case of Sannekka E. From the result, it is suggested that the application of Sannekka E increases SPS activity, which promotes the synthesis of sucrose from glucose and fructose in melon fruits.