Hydrellia prosternalis Deeming, a leaf-mining ephydrid fly, has been recently considered an important insect pest attacking rice leaves. Influence of certain cultural practices on the incidence of this insect in - rice fields was studied for two successive seasons; 1995 and 1996 at the experimental farm of Rice Research and Training Center (RRTC), Sak­ha. Rice sown on May 1st had the least infestation (3.63 - 4.75%) and received the lowest number of eggs (1.56-1.75 / 100 rice leaves). The rice leaf miner (RLM) incidence increased gradually and significantly as the sowing date was later. Rice sown after the end of May suffered from severe RLM infestation (56.63 - 64.17 and 68.67-69.17% for 1 June and 15 June cultivations, respectively). Permanent flooded rice plots proved to encourage the RLM inci­dence, having 57.50% infestation, and this level was gradually de­creased as the irrigation intervals prolonged. Infestation rates were 42.50, 22.86 and 18.95% at 6,9 and 12-day intervals, respectively. It was apparent that plant densities had no effect on RLM infes­tation. Plots of transplanting spacings at 10 x 10 and 10 x 15 cm were less infested by RLM than those of wider spaces; 20 x 20, 20 x 30 and 30 x 30 cm during two weeks after transplanting. When the time elapsed, no RLM infestation differences were detected due to trans­planting spacing beginning from the third week after transplanting.