A new method of arthroscopic partial meniscectomy for horizontal tear of discoid lateral meniscus was devised to preserve as much meniscal tissue as possible. To evaluate the clinical result of this method for horizontal tear of discoid lateral meniscus, 31 knees (30 patients) were reviewed at an average follow-up of 35 months (range 14-48 months). Horizontally torn discoid lateral menisci were classified as incomplete (11 cases) or complete (20 cases) by the Watanabe classification; no Wrisberg type was noted. Partial meniscectomy was performed in all cases. For the technique of a new method of partial meniscectomy, the unstable leaf of the horizontally torn meniscus was removed to the peripheral rim, but the stable one was preserved and reshaped to produce the similar appearance to the normal lateral meniscus in terms of width and thickness. It was trimmed to have a balanced rim of meniscal tissue about 6-8 mm in width. Meniscal repair was added to partial meniscectomy in one case. All the cases were rated using the Lysholm Knee Scoring Scale and were reviewed to recognize retear clinically. The scores increased after partial meniscectomy by average 20.7 (from 73.0 to 93.7). Recurrence of tear or aggravation of symptoms was not noted at the final follow-up.