The effects of crude Kalajira and its ethanol extract (freecc dried). sent glucose concentration in streptownwin ($R) induced diabetic rats were compared among 63 healthy adult rats of both sexes and the experiments were divided into three parts. Ran were divided into gnmps and the effects of single ip. injection of STZ at a dose .150 mg/ kg b.u, on serum glucose concentration of normal rats was studied and compared with control. The effects of crude nigella at a dose of 6 gin / kg b. wt./ day an with food on season glucose concentration of $TZ treated diabetic rats were studied. The serum glucose concentration in erode nigella.treated normal nay was 5.4819.22 mmol/1. and that in crude nigella.treated diabetic rats was 1330.0.34anntoill- signfficandy lower (P<0.001) when compared to STZ-treated diabetic rats (10.37x0.18 ostool/U. Later. freeke.dried ethanol extract of nigella was used and the serum glucose concentration was 4.90,0.32 nono1/1. and the serum glucose concentration of those of crude nigella.treated diabetic rats ions 6.8710.31nonoUL Here also was significant reduction of serum glucose concentration (P<0.001) compared to those of $TZ control groups. The reduction of serum glucose concentration in diabetic rats following oral administration of made nigella powder (6gm /kg b. in. /day) mixed with food and freeke.dried ethanol canal of nigella (6gm/ kg b. on. /day) mixed with food far 21 days were statistically significant (1,09.0011 compared to 17Z control but not significant IP>0.05) compared to each other suggesting that both crude pawl., and freeke.dried ethanol extract of nigella hare similar efficacy in reducing wont glucose concentrations of $12. induced diabetic rats. Further studies have been suggested to know the mechanism of anti.diabetic effects of nigella and to know ilteaitttilor effects of various extmcks of nigella upon blood sugar level of diabetic rats.