In order to study the effect of feeding rapeseed oil meal (ROM) treated with enzyme hydrolysis, ammoniation and iodine supplementation on rats, a feeding experiment was conducted. Thirty-six male Wistar rats of 25-27days old were divided into 6 groups and housed randomly in the individual cages. Each group was placed on one of the following six experimental diets; Basal+ROM (Local), Basal+ROM (Canadian), Basal+ROM (Local) hydrolyzed with mustard seed powder, Basal+Ammoniated ROM (Local), Basal+ROM (Local)+lodine (KI) supplementation, and Basal+ROM (Local) hydrolyzed with mustard seed powder+lodine supplementation. Rats were kept for 6 weeks. Weight gain, feed intake, feed efficiency and weight of thyroid glands, kidneys and liver were measured. The results obtained are summarized as follows: 1. Weight gains of the rats fed Basal+Canadian ROM (225.7g), Basal+Ammoniated Local ROM (219.5g) and Basal+Local ROM (218.6g) were significantly (P$lt;0.01) greater than that of Basal+Local ROM hydrolyzed with mustard seed powder+Iodine (173.7g). 2. Feed intakes of rats fed Basal+Ammoniated Local ROM (683.8g), Basal+Canadian ROM (663.3g) and Basal+Local ROM (662.7g) were significantly (P$lt;0.01) greater than that of rats fed Basal+Local ROM hydrolyzed with mustard seed powder+Iodine (542.1g). 3. The differences among treatments in feed efficiency were not statistically significant. 4. The weights of thyroid glands (per 100g body weight) of rats fed Basal+Local ROM hydrolyzed with mustard seed powder (0.285g) and Basal+Local ROM hydrolyzed with mustard seed Powder+Iodine (0.263g) were significantly (P$lt;0.01) heavier than those of the rats fed Basal+Local ROM+lodine (0.123g), Basal+ Canadian ROM (0.137g), Basal+Ammoniated Local ROM (0.142g) and Basal+Loca1 ROM (0.184g). 5. The liver weight (per 100g body weight) of rats fed Basal+Local ROM (0.137g) was significantly (P$lt;0.01) heavier than those of rats fed Basal+Local ROM+Iodine (0.104g) and Basal+Local ROM hydrolyzed with mustard seed powder+Iodine (0.109g). 6. The weight of kidneys (per 100g body weight) of rats fed Basal+Local ROM (0.027g) was significantly (P$lt;D.O1) heavier than those of rats fed Basal+Local ROM+Iodine (0.021g) and Basal+Loca1 ROM hydrolyzed with mustard seed powder+lodine (0.020g).