To study effects of intratesticular injection of AgNO3 and latic acid solution(ALS) on castration, 50 heads of crossbred(Large Yorkshire$ imes$Landrace) pigs were used. ALS(1% or 5% in concentration) was injected(0.2ml or 0.5ml in amout) to testes of pigs(weighing 7.7kg) unilaterally or bilaterally and changes of scrotum size, residual concentration of Ag, and steroid concentration in the blood were measured. The results obtained are summarized as follows : 1. The size of testis became swollen significantly(p<0.01) on the 3rd day after the treatment and then reduced to the same size before the treatment on the 26th day. 2. The residual concentration of Ag in the bilaterally treated pigs was similar to that of the control pigs, while it was lower in the unilaterally treated pigs than in the control pigs except the 1%-0.2ml treated pigs whose concentration was similar to that of the control pigs. 3. In 92 days after the bilateral injection, the testosterone concentration was higher significantly(p<0.01) in the 5%-0.5ml treated pigs than in the control pigs. However, in 120 days it was lower significantly(p<0.05) in the treated pigs than in the control pigs. 4. In 92 days after the bilateral treatment, the androstenedione concentration was lower significantly(p<0.01) in the 1%-0.5ml treated pigs than in the control pigs and it was also lower significantly(p<0.05) in the 1% or 5% treated pigs than in the control pigs on the 120th day after the treatment.