Abstract: Wind pollinated progenies of 11 different high-gum-yielding Slash families have been tested at Xinyi County,Guangdong Province for oleoresin yield since 1986 (5 families) and 1989 (7 families).Oleoresin yield by means of chipping stem was measured in 1991 and the results showed that there were significant differences among families with age of 6 and 3 years respectively in oleoresin yield,height,DBH and crown growth.Genetic variation among families accounted for 13.08%~28.90% for basic oleoresin yield capacity (oleoresin yielded by level wound of 1cm length) and 9.70%-27.18% for potential oleoresin yield capacity (basic oleoresin yield capacity multiplied by the circumference of stem).The averaged oleoresin yield of high-gum-yielding families for both,ages was about 61% higher than those of the commercial seeds.