Population fluctuations of adult sweetpotato whitefly (Bemisia tabaci Gennadius) were monitored at the Agricultural Experiment Station, College of Agriculture, Sultan Qaboos University, Sultanate of Oman, for a period of four years on a weekly basis from 1st week of January 1993 through December 1996 by using yellow sticky traps. The pest was ubiquitous all round the year as it was found in all the weekly recordings in the four-year study. However, its activity was at peak with large populations from July to October. During 1993, 1994 and 1995 the highest catch of whitefly adults were recorded in the month of September. However, during 1996, the highest catch was recorded in August. Thereafter, whitefly populations started to decrease, fluctuating at lower levels during the other months. The effect of certain weather parameters revealed that the highest adult catches occurred when the maximum temperatures ranged from 32.6 to 40.8°C and the minimum temperatures were 23.7 to 32.0°C. while the maximum relative humidities ranged from 57 to 92% and minimum relative humidities ranged from 13 to 67%. The correlation analyses of four years pooled data revealed that both temperature and relative humidity have positive and significant effect on the activity of the adult whitefly. The 'r' value for maximum temperature was 0.15 However, the effect of maximum relative humidity was more profound (r = 0.33).