Over 750 young people aged 9 to 17 will take part in the first of three semi-finals at the Crystal Palace National Sports Centre in London on Sunday.
The second and third semi-finals are at Millfield School in Street, Somerset and at Macclesfield Leisure Centre in Macclesfield, both on Sunday 27 January.
The Championships are organised and run by Pentathlon GB, the national governing body for the Olympic sport of Modern Pentathlon and gives young people the opportunity to participate in an exciting multi-sport competition.
Athletes tackle a run and a swim in seven age groups from Year 5 to Year 12/13, with a separate competition for teachers. Those in Year 5, 6 and 7 and teachers, face a 50m swim and 500m run, while Years 8, 9, 10/11 and 12/13 tackle a 100m swim and 1000m run.
The top athletes in each age group qualify places for the British Championships finals at Crystal Palace on Sunday 24 March – when they will have the chance to battle it out for the national titles.
Some of Britain’s most talented modern pentathletes competed in the event in the past, including Jamie Cooke, who went on to win the 2011 World Junior Championships and Kate French, runner-up at last year’s European Junior Championships.