The present study was conducted to calibrate and predict the growth and yield of Brassica juncea under semi-arid environment of Delhi region using InfoCrop model. Field experiments were carried out with the variety Pusa Jaikisan (most popularly grown in north western parts of India), sown on 15th and 30th October of rabi, 2005-06 and 2006-07 on sandy clay loam textured soils at research farm of Indian Agricultural Research Institute (IARI), New Delhi. The base temperature at different phenological stages was taken as 50C. The thermal time from germination to flowering was calibrated to 7300D. Crop growth parameters like leaf area index (LAI), biomass and seed yield were simulated using InfoCrop model. The model overestimated LAI and biomass at the initial crop growth stages but underestimated at the peak/maximum level. The model overestimated the seed yield for both the sowings and the seasons. Actual seed yield was of the order of 23 to 37 q ha-1 while the simulated yield was of the order of 37 to 42 q ha-1 with a RMSE value of 3.14 indicating significant differences between observed and simulated yield. The model needs further refinement.