Abstract: Forty-five C57BL/6 mice were randomly divided into five groups（A-E）. Group B and D served as the control group of A and C. Each mouse of group A was intraperitoneally injected with 0.1 ml whole worm extract of Ascaris lumbricoides every other day, and 10 days later injected with 0.1 ml Lewis lung carcinoma（LLC） cells at right axillary subcutaneously region. Mice of group B were injected with normal saline and then developed tumor model. Each mouse of group C was injected with 0.1 ml LLC cells, and two days later, injected with 0.1 ml whole worm extract of A.lumbricoides every other day for 5 times. After the tumor model developed, mice in group D were injected with normal saline. Group E was the negative control group. Time intervals between implantation and active growth and tumor weight were recorded. Tumor inhibition rate was calculated. The average time interval between tumor implantation and measurable tumor growth for groups A, B, C and D was （7.0±1.1）, （6.0±0.7）, （9.0±1.2） and （7.0±0.9） days. Tumor weight of group A [（722.2±413.5） mg] was heavier than that of group B [（338.9±282.2） mg] （P＜0.05）. The tumor inhibition rate was the highest in group C （33.3%）. Tumor weight of group C [（237.8±101.8） mg] was lighter than that of group D [（356.7±176.9） mg] （P＜0.05）. The results indicated that the tumor formation is affected by the whole worm extract of A. lumbricoides which may have an inhibitory effect on tumour growth.

Key words: Ascaris lumbricoides, Extract, Lewis lung carcinoma cell, Tumor inhibition activity