The aim is to compare the acute skin toxicity between two different fractionation schedules of adjuvant whole breast radiotherapy, conventional fractionation radiotherapy and hypofractionated radiotherapy. This is a prospective study of breast cancer patients referred for adjuvant radiation therapy. Radiation therapy was given either as conventional fractionation radiotherapy (5000 cGy/ 25 fractions / 5 weeks) or hypofractionated radiotherapy (4005 cGy/15 fractions / 3 weeks). Acute RT toxicity was evaluated using the Radiation Therapy Oncology Group toxicity grading system; the incidence of radiation therapy toxicity was compared. Seventy-eight patients were accrued in the study, 58% had breast conservative surgery and 42% had modified radical mastectomy. 54% were treated with hypofractionated radiotherapy and 46% with conventional fractionation radiotherapy, while 64% had Grade 0-II radiation therapy toxicity and 36% had Grade III-IV toxicity. On univariate analysis, the incidence of radiation therapy toxicity was (52.8%) in conventional fractionation radiotherapy group as compared to 21.4% in hypofractionated radiotherapy group (p = 0.004); other variables were not statistically significant. On multivariate analysis radiotherapy fractionation was the only factor of statistical significance regarding the incidence of radiation reaction (p = 0.03). This study showed fewer incidences of acute radiation reactions in hypofractionated arm as compared to conventional fractionated arm in the adjuvant whole breast radiotherapy.