The present study pertained to records on milk production and milk constituents of 303 Murrah buffaloes with 769 lactations spread over a period of 11 years from 1989 to 1999, collected from DCB Division of NDRI, Kamal, Haryana. To study the effect of various genetic and non-genetic factors on milk yield and milk constituent traits, mixed model least-squares analysis was used fa analysis of data. Overall least squares means for all lactation trails of lotal milk yield (TMY), milk yield in 305 days or Jess (305MY), lactation average fat (LFA), average solids-not-fal (LSA), average total solids (LTA) percentages, lactation at yield(LFY), solids-nat-fat yield(LSY), total solids yield (LTY) and 6% fat corrected milk (FCMY) yield were 2505.53±33.31 kg, 2342.47±27.20 kg, 8.06±0.50%, 9.58±0.03%, 17.65±0.51%, 201.22±10.10 kg, 240.13±3.28 kg, 441.35±11.35 kg and 3093.72±119.37 kg, respectively. Analysis of variance showed that the differences were statistically significant for effect of sire on TMY, 305MY, LSA, LSY and LTV; season on TMY and LSY; period on TMY, 305 MY, LSA. LSY and LTV; and parity on TMY, 305 MY and LSY.