A study was undertaken to estimate the Heterosis effects in maize at Agricultural Research Station Baffa, Mansehra during 2014 and 2015 to identify combinations expressing high hybrid vigor. The 31 F₁ were planted along with their 7 parents during Kharif 2015. The Maximum positive heterosis was shown by  Azam x Shaheen  (35.1%) for stem girth,  Jalal x Kissan (35.7%) for leaf area, Jalal x Kissan (40.0%) for number of cobs plant^-1, EV-2 x Shaheen (18.0%) for number of cobs plot^-1, EV-2 x Jalal (28.6%) for  fresh cobs weight, Sadaf x Shaheen (19.2%) for cob length, Pahari x Sadaf and EV-2 x Shaheen (4.4%) for cob girth,  Pahari x Kissan (4.8%) for number of grain rows, Pahari x Sadaf (10.8%) for number of grains row^-1,  EV-2 x Jalal (33.9%) for plant weight, Azam x Kissan (20.0%) for dry cobs weight, Kissan x Azam (21.7%) for shelling percentage,  Sadaf x Jalal (75.5%) for grains weight after shelling and cross of Sadaf x Jalal (4.8%) for dry 100 grains weight. While cross of Kissan x Jalal and Jalal x Kissan showed maximum negative heterosis (-11.6%) for days to germination, Kissan x Jalal and Jalal x Kissan (-11.6%) for days to 50% tasseling, Jalal x Azam (-5.1%) for days to 50% silking, Kissan x EV-2 (-17.9%) for plant height, Sadaf x Shaheen (-15.1%) for internode length, Azam x Sadaf (-4.9%) for   ear height, Azam x Kissan (-11.4%) for fresh cobs moisture percentage and cross of  EV-2 x Jalal (-13.7%) for dry cobs moisture percentage.

Key Words: Heterosis, Cross, Days, Length, Hight, Weight.